My attempts to get mscoree.tlb loaded at runtime with powershell. The working code is EnumAppDomains.ps1

dynamic.ps1

# adapted from here http://blog.semanticsworks.com/2008/04/enumerating-appdomains.html

$csharpString = @"
using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;

public class ListProcessAppDomains
{
    private static extern void LoadTypeLibEx
        (String strTypeLibName, RegKind regKind, 
         [MarshalAs( UnmanagedType.Interface )] out Object typeLib);

    private enum RegKind
    {
        RegKind_Default = 0,
        RegKind_Register = 1,
        RegKind_None = 2
    }

    private class ConversionEventHandler : ITypeLibImporterNotifySink
    {
        private void ReportEvent( ImporterEventKind eventKind, int eventCode, string eventMsg )
        {
            Console.Error.WriteLine("Kind: {0} Code: {1} Message");
        }
    
        public Assembly ResolveRef( object typeLib )
        {
            // resolve reference here and return a correct assembly...
      //This is where im not sure how to do it
	    return null; 
        }    
    }

    static ListProcessAppDomains() {

    }

    public static IList<AppDomain> GetAppDomains()
    {
        var appDomains = new List<AppDomain>();
        IntPtr enumHandle = IntPtr.Zero;
        dynamic host = Activator.CreateInstance(Type.GetTypeFromProgID("CLRMetaData.CorRuntimeHost"));
        try
        {
            host.EnumDomains(out enumHandle);
            object domain = null;
            while (true)
            {
                host.NextDomain(enumHandle, out domain);
                if (domain == null) break;
                AppDomain appDomain = (AppDomain)domain;
                appDomains.Add(appDomain);
            }
            return appDomains;
        }
        catch (Exception e)
        {
            Console.Error.WriteLine(e.ToString());
            return null;
        }
        finally
        {
            host.CloseEnum(enumHandle);
            Marshal.ReleaseComObject(host);
        }
    }
}
"@

Add-Type -TypeDefinition $csharpString

EnumAppdomains,poshv2.ps1

$tlbName = Split-Path -Parent ([AppDomain]::CurrentDomain.GetAssemblies() | Where { $_.Location -Match '\\mscorlib.dll$' }).Location 
$tlbName = Join-Path $tlbName 'mscoree.tlb';

$csharpString = @"
//adapted from here http://blog.semanticsworks.com/2008/04/enumerating-appdomains.html
using System;
using System.Collections.Generic;
using System.Reflection;
using System.Reflection.Emit;
using System.Runtime.InteropServices;

public class ListProcessAppDomains
{

    [DllImport( `"oleaut32.dll`", CharSet = CharSet.Unicode, PreserveSig = false )]
    private static extern void LoadTypeLibEx
        (String strTypeLibName, RegKind regKind, 
         [MarshalAs( UnmanagedType.Interface )] out Object typeLib);

    private enum RegKind
    {
        Default = 0,
        Register = 1,
        None = 2
    }

    private class ConversionEventHandler : ITypeLibImporterNotifySink
    {
        public void ReportEvent( ImporterEventKind eventKind, int eventCode, string eventMsg )
        {
            Console.Error.WriteLine("Kind: {0} Code: {1} Message");
        }
    
        public Assembly ResolveRef( object typeLib )
        {
            string stackTrace = System.Environment.StackTrace;
            Console.WriteLine("ResolveRef ({0})", typeLib);
            Console.WriteLine(stackTrace);
          return null; 
        }    
    }

    public static AssemblyBuilder LoadMsCoreeDll( ref Object typeLib ) {
        ConversionEventHandler eventHandler = new ConversionEventHandler();
        string assemblyName = "PoshComWrapper.dll";
        LoadTypeLibEx( @"$($tlbName)", RegKind.None, out typeLib ); 
        TypeLibConverter typeLibConverter = new TypeLibConverter();
        return typeLibConverter.ConvertTypeLibToAssembly( typeLib, assemblyName, 0, eventHandler, null, null, null, null );
    }
}
"@

# So we can run this scipt multiple times
try { [ListProcessAppDomains] } catch {  Add-Type -TypeDefinition $csharpString }

function Get-AppDomain {
    $typeLib = $null;
    $assemblyBuilder = [ListProcessAppDomains]::LoadMsCoreeDll([ref] $typeLib)
    $corRuntimeHostClass = $assemblyBuilder.CreateInstance('PoshComWrapper.CorRuntimeHostClass')
    $enumHandle = [IntPtr]::Zero
    $corRuntimeHostClass.EnumDomains([ref] $enumHandle);
    $appDomain = $null;
    do
    {
        $corRuntimeHostClass.NextDomain($enumHandle, [ref] $appDomain);
        if ($appDomain -ne $null -and $appDomain.GetType() -eq [AppDomain]) { $appDomain; }
    } while ($appDomain -ne $null)
}

Get-AppDomain 

EnumAppDomains.ps1

$tlbName = Split-Path -Parent ([AppDomain]::CurrentDomain.GetAssemblies() | Where Location -Match '\\mscorlib.dll$').Location
$tlbName = Join-Path $tlbName 'mscoree.tlb';

$csharpString = @"
//adapted from here http://blog.semanticsworks.com/2008/04/enumerating-appdomains.html
using System;
using System.Collections.Generic;
using System.Reflection;
using System.Reflection.Emit;
using System.Runtime.InteropServices;

public class ListProcessAppDomains
{

    [DllImport( `"oleaut32.dll`", CharSet = CharSet.Unicode, PreserveSig = false )]
    private static extern void LoadTypeLibEx
        (String strTypeLibName, RegKind regKind, 
         [MarshalAs( UnmanagedType.Interface )] out Object typeLib);

    private enum RegKind
    {
        Default = 0,
        Register = 1,
        None = 2
    }

    private class ConversionEventHandler : ITypeLibImporterNotifySink
    {
        public void ReportEvent( ImporterEventKind eventKind, int eventCode, string eventMsg )
        {
            Console.Error.WriteLine("Kind: {0} Code: {1} Message");
        }
    
        public Assembly ResolveRef( object typeLib )
        {
            var stackTrace = System.Environment.StackTrace;
            Console.WriteLine("ResolveRef ({0})", typeLib);
            Console.WriteLine(stackTrace);
          return null; 
        }    
    }

    public static AssemblyBuilder LoadMsCoreeDll( ref Object typeLib ) {
        var eventHandler = new ConversionEventHandler();
        var assemblyName = "PoshComWrapper.dll";
        LoadTypeLibEx( @"$($tlbName)", RegKind.None, out typeLib ); 
        var typeLibConverter = new TypeLibConverter();
        return typeLibConverter.ConvertTypeLibToAssembly( typeLib, assemblyName, 0, eventHandler, null, null, null, null );
    }
}
"@

# So we can run this scipt multiple times
try { [ListProcessAppDomains] } catch {  Add-Type -TypeDefinition $csharpString }

function Get-AppDomain {
    $typeLib = $null;
    $assemblyBuilder = [ListProcessAppDomains]::LoadMsCoreeDll([ref] $typeLib)
    $corRuntimeHostClass = $assemblyBuilder.CreateInstance('PoshComWrapper.CorRuntimeHostClass')
    $enumHandle = [IntPtr]::Zero
    $corRuntimeHostClass.EnumDomains([ref] $enumHandle);
    $appDomain = $null;
    do
    {
        $corRuntimeHostClass.NextDomain($enumHandle, [ref] $appDomain);
        if ($appDomain -ne $null -and $appDomain.GetType() -eq [AppDomain]) { $appDomain; }
    } while ($appDomain -ne $null)
}

Get-AppDomain 

LoadTypeLibEx.ps1

Add-Type -Namespace "JustAProgramer" -Name 'LoadTypeHelper' -MemberDefinition "[ DllImport( `"oleaut32.dll`", CharSet = CharSet.Unicode, PreserveSig = false )]
    public static extern void LoadTypeLibEx( String strTypeLibName, RegKind regKind, 
        [ MarshalAs( UnmanagedType.Interface )] out Object typeLib );
    public enum RegKind
    {
        RegKind_Default = 0,
        RegKind_Register = 1,
        RegKind_None = 2
    }"

$tlbName = 'C:\Windows\Microsoft.NET\Framework64\v4.0.30319\mscoree.tlb';
$dllName = [IO.Path]::GetTempFileName()

$typeLibConverter = New-Object Runtime.InteropServices.TypeLibConverter

$typeLib = $null;
[JustAProgramer.LoadTypeHelper]::LoadTypeLibEx( $tlbName, [JustAProgramer.LoadTypeHelper+RegKind]::RegKind_None, [ref] $typeLib ); 
#$typeLibConverter | gm
#$typeLibConverter.ConvertTypeLibToAssembly
$typeLib
[AssemblyBuilder] $asm = $typeLibConverter.ConvertTypeLibToAssembly($typeLib, $dllName, 0, $null, $null, $null, $null, $null );    
$asm.Save( "ExplorerLib.dll" );


if (Test-Path $dllName) {
    rm -Force $dllName
}

Program.cs

using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using mscoree;


// This code does not work in .NET 4.0. It does compile in .NET 3.5
namespace ConsoleApplication2
{
    internal  static class Program
    {
        static void Main()
        {
            foreach (var appDomain in GetAppDomains())
            {
                Console.WriteLine("Name: {0} Id: {1} Config file: {2}", appDomain.FriendlyName, appDomain.Id, appDomain.SetupInformation.ConfigurationFile);
            }

            Console.Write("Press any key to continue . . . ");
            Console.ReadKey(true);
        }

        private static IList<AppDomain> GetAppDomains()
        {
            var appDomains = new List<AppDomain>();
            IntPtr enumHandle = IntPtr.Zero;
            var host = new CorRuntimeHostClass();
            try
            {
                host.EnumDomains(out enumHandle);
                object domain;
                do
                {
                    host.NextDomain(enumHandle, out domain);
                    if (domain == null) break;
                    var appDomain = (AppDomain) domain;
                    appDomains.Add(appDomain);
                } while (domain != null);
            }
            catch (Exception e)
            {
                Console.WriteLine(e.ToString());
                return null;
            }
            finally
            {
                host.CloseEnum(enumHandle);
                Marshal.ReleaseComObject(host);
            }
            return appDomains;
        }
    }
}