a simple script to build a WinPE image ( this is far from perfect but does the job for me )

Build-WinPE.ps1

# requires -Version 4
# Requires -RunAsAdministrator

<#

.SYNOPSIS
   Create a custom WinPE image from scratch

.DESCRIPTION
   This CmdLet allows you to create a custom WinPE image from Scratch

.EXAMPLE
   Another example of how to use this cmdlet

.NOTES
 ScriptName  : Build_WinPE.ps1
 Author      : Marco Micozzi 
 Date        :
 License     : GPL v3
 Requirements: ADK
 
#>

#region Parameters
[CmdLetBinding()]
Param(

    [Parameter(Mandatory = $true)]
    [ValidateSet('8.1', '10')]
    [string] $Version,
    
    [Parameter( HelpMessage = 'The CPU architecture, can be either x86, amd64 or ia64.', Mandatory = $false)]
    [ValidateSet('x86', 'amd64', 'ia64')]
    [Alias('CPU', 'arc', 'proc')]
    [string] $Architecture = 'amd64',
    
    [Parameter( HelpMessage = 'Set the language used in the WinPE environment. Defaults to en-us')]
    [ValidateSet('en-us', 'en-gb', 'nl-be', 'nl-nl', 
                 'de-de', 'it-it', 'fr-fr', 'fr-be')]
    [Alias('inlang')]
    [string] $InputLanguage = 'nl-be',

    [Parameter( HelpMessage = 'Set the language used in the WinPE environment. Defaults to en-us')]
    [ValidateSet('en-us', 'en-gb', 'nl-be', 'nl-nl', 
                 'de-de', 'it-it', 'fr-fr', 'fr-be')]
    [Alias('syslang')]
    [string] $SystemLanguage = 'en-us',

    [Parameter( HelpMessage = 'The label of the produced ISO image file.')]
    [Alias('Label', 'lbl')]
    [string] $ISOLabel = 'Custom WinPE',

    [Parameter( HelpMessage = 'The temporary directory where the PE will be built.')]
    [Alias('BuildDir', 'blddir', 'bldir')]
    [string] $BuildDirectory = 'C:\Temp\WinPE',

    [Parameter( HelpMessage = 'Clean the BuildDirectory before starting the script')]
    [switch] $Clean,

    [Parameter( HelpMessage = 'Define a list of optional packages to add to the WinPE')]
    [Alias('pkg')]
    [ValidateSet('HTA', 'WMI', 'Scripting', 'NetFX', 'PowerShell', 
                 'StorageWMI', 'DismCmdlets', 'LegacySetup')]
    [string[]] $Packages = @('HTA', 'WMI', 'NetFX', 'Scripting', 'PowerShell', 'StorageWMI', 'DismCmdlets'),

    [Parameter( HelpMessage = 'Indicates that an ISO should be created for the custom WinPE.' )]
    [Alias('Make', 'Build', 'm')]
    [switch] $MakeIso

)

# BUG: the script fails if the build directory exists
#endregion Parameters

#region Imports
# Import the module with common functions
#Import-Module $PSScriptRoot\common.psm1
#endregion Imports

#region Variables
[string] $MountDirectory = "$BuildDirectory\mount"
[string] $BootWIM        = "$MountDirectory\ISO\sources\boot.wim"

#System32 is used in all Architecture types for our purposes.
[string] $SystemPath     = "$MountDirectory\Windows\System32"  
#endregion


#region Set Path

[string] $KitsRoot = "C:\Program Files (x86)\Windows Kits\$Version"  #Get-KitsRoot

#[string] $ADKInstallationPath = "$(Get-ProgramFiles32)\Windows Kits\8.1\Assessment and Deployment Kit"
[string] $ADKPath = "$KitsRoot\Assessment and Deployment Kit"

[string] $DandIRoot = "$ADKPath\Deployment Tools"

[string] $WinPERoot = "$ADKPath\Windows Preinstallation Environment"

[System.Environment]::SetEnvironmentVariable("WinPERoot", $WinPERoot, "process")

# not sure if I should be using this here: $env:PROCESSOR_ARCHITECTURE 
[string] $DismRoot    = "$DandIRoot\$Architecture\DISM"

[string] $BCDBootRoot = "$DandIRoot\$Architecture\BCDBoot"

[string] $ImagingRoot = "$DandIRoot\$Architecture\Imaging"

[string] $OSCDImgRoot = "$DandIRoot\$Architecture\Oscdimg"

[System.Environment]::SetEnvironmentVariable("OSCDImgRoot", $OSCDImgRoot, "process")

[string] $WdsmcastRoot = "$DandIRoot\$Architecture\Wdsmcast"

[string] $HelpIndexerRoot = "$DandIRoot\HelpIndexer"

[string] $WSIMRoot = "$DandIRoot\WSIM"

[string] $NewPath = "$DISMRoot;$ImagingRoot;$BCDBootRoot;$OSCDImgRoot;$WdsmcastRoot;$HelpIndexerRoot;$WSIMRoot;$WinPERoot;"

# store the old path
[string] $OldPath = $Env:Path

[System.Environment]::SetEnvironmentVariable("PATH", $NewPath + "$env:SystemRoot\System32", "process")

#$Env:Path = $NewPath

#endregion

if ( Get-Module -Name Dism ) { 
    Remove-Module -Name Dism
}
Import-Module $DismRoot

Clear-WindowsCorruptMountPoint | Out-Null

# clean up all mounted images
Get-WindowsImage -Mounted | ForEach-Object {    
    Write-Host "Unmounting old mount in '$($_.Path)'"
    Dismount-WindowsImage -Path $_.MountPath -Discard  | Out-Null
}

# clean the temp dir
if ( $Clean.IsPresent ) {    
    if ( Test-Path -Path $BuildDirectory ) {
        Remove-Item -Path $BuildDirectory -Recurse -Force         
    }
}

#Run Dism Cleanup... not sure if needed...?
Write-Host "Running Imagex /Cleanup..." -NoNewline
Dism /Cleanup-Wim
Write-Host " done" -ForegroundColor Green

#Run CopyPE.cmd to create the initial WinPE Image
Write-Host  "Running CopyPE..." -NoNewline
copype.cmd $Architecture $BuildDirectory
Write-Host " done" -ForegroundColor Green


Write-Host "Mount the image" -NoNewline

Try {
    $Mount = Mount-WindowsImage -ImagePath "$BuildDirectory\media\sources\boot.wim" -Index 1 -Path $MountDirectory
    Write-Host " done" -ForegroundColor Green
}
Catch{
    $message = "TRAPPED: {0}: '{1}'" -f ($_.Exception.GetType().FullName), ($_.Exception.Message)
    Write-host "FAILED" -ForegroundColor Red
    Exit
}


Write-Host "Adding Packages" -ForegroundColor Yellow

$Packages | ForEach-Object {

    [string] $Package = "$WinPERoot\$Architecture\WinPE_OCs\WinPE-$_.cab"
    [string] $PackageLang = "$WinPERoot\$Architecture\WinPE_OCs\$SystemLanguage\WinPE-$($_)_$SystemLanguage.cab"
    
    if ( ( Test-Path -Path $Package ) -and ( Test-Path -Path $PackageLang ))
    {       

        Write-Host "`tAdding $_" -ForegroundColor Yellow
        Try{
            Add-WindowsPackage -PackagePath $Package -Path $MountDirectory -IgnoreCheck | Out-Null
            Add-WindowsPackage -PackagePath $PackageLang -Path $MountDirectory -IgnoreCheck | Out-Null
            Write-Host "Done" -ForegroundColor Green
        }
        Catch{
            Write-Host "Failed" -ForegroundColor Red
        }        
    }
    else
    {
        Write-Error "couldn't find: '$Package' or '$PackageLang'!"
    }
    
}

Write-Host 'Set the input language' -ForegroundColor Yellow

Dism /image:"$MountDirectory" /Set-SysLocale:"$SystemLanguage"

Dism /image:"$MountDirectory" /Set-UserLocale:"$SystemLanguage"

Dism /image:"$MountDirectory" /Set-InputLocale:"$InputLanguage"

Copy-Item -Path "C:\Windows\System32\whoami.exe" -Destination "$SystemPath" -Force

Copy-Item -Path "C:\Windows\System32\shutdown.exe" -Destination "$SystemPath" -Force

#Copy-Item -Path "C:\Projects\Personal\NEW\todo\WinPE\Script\utilities\Winpeshl.ini" -Destination "$MountDirectory\Windows\System32\"

Write-Host 'Unmount the image' -NoNewline

Dismount-WindowsImage -Path $MountDirectory -Save

Write-Host " done" -ForegroundColor Green

if ( $MakeIso ){    

    Write-Host "Building ISO File in '$BuildDirectory\WinPE_$Architecture.iso'" -ForegroundColor Yellow

    [string] $BOOTDATA="1#pEF,e,b`"$BuildDirectory\fwfiles\efisys.bin`""

    if ( Test-Path -Path "$BuildDirectory\fwfiles\etfsboot.com" ){

        $BOOTDATA="2#p0,e,b`"$BuildDirectory\fwfiles\etfsboot.com`"#pEF,e,b`"$BuildDirectory\fwfiles\efisys.bin`""

    }
    
    oscdimg -l"$ISOLabel" -bootdata:$BOOTDATA -u1 -udfver102 "$BuildDirectory\media" "$BuildDirectory\WinPE_$Architecture.iso" 

}

[System.Environment]::SetEnvironmentVariable("PATH", $OldPath, "process")

Remove-Module Dism