Rough cut of where I got in passing project parameters in to an SSIS package that uses the project deployment model but isn't stored in the SSISDB

Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Microsoft.SqlServer.Dts.Runtime;

namespace ParameterPasser
{
    /// <summary>
    /// http://stackoverflow.com/a/26012658/181965
    /// </summary>
    class MyEventListener : DefaultEvents
    {
        public override void OnInformation(DtsObject source, int informationCode, string subComponent, string description, string helpFile, int helpContext, string idofInterfaceWithError, ref bool fireAgain)
        {
            base.OnInformation(source, informationCode, subComponent, description, helpFile, helpContext, idofInterfaceWithError, ref fireAgain);
            
            Console.WriteLine("Info in {0}/{1} : {2}", source, subComponent, description);
        }

        public override bool OnError(DtsObject source, int errorCode, string subComponent, string description, string helpFile, int helpContext, string idofInterfaceWithError)
        {
            Console.WriteLine("Error at {0}/{1} : {2}", source, subComponent, description);
            return false;
        }

        public override void OnTaskFailed(TaskHost taskHost)
        {
            Console.WriteLine(taskHost.Name);
        }

    }


    class Program
    {
        static void Main(string[] args)
        {
            string packagePath = string.Empty;
            string isPacPath = @"C:\sandbox\so_31812951\so_31812951\bin\Development\so_31812951.ispac";
            string packageName = "Package.dtsx";

            // Has a package level parameter but no project
            packagePath = @"C:\sandbox\so_31812951\so_31812951\Package_solo.dtsx";

            Application app = new Application();
            Package pkg = null;

            // https://msdn.microsoft.com/en-us/library/ff930196(v=sql.110).aspx
            Project proj = null;
            PackageItem pi = null;
            MyEventListener eventListener = null;
            eventListener = new MyEventListener();

            ///////////////////////////////////////////////////////////////////
            // Run an SSIS package that has a package parameter
            ///////////////////////////////////////////////////////////////////
            pkg = app.LoadPackage(packagePath, eventListener);

            // This is how we specify a package parameter value
            pkg.Parameters["PackageParam"].Value = 1;

            var results = pkg.Execute();
            Console.WriteLine(results.ToString());

            ///////////////////////////////////////////////////////////////////
            // Run an SSIS package that has a Project parameter
            ///////////////////////////////////////////////////////////////////
            proj = Project.OpenProject(isPacPath);

            proj.Parameters["ProjectParameter"].Value = 10;
            pi = proj.PackageItems[packageName];

            // Yes, I can see the project parameters in there
            foreach (var item in proj.PackageItems)
            {
                Console.WriteLine(item.StreamName);
            }

            pi.LoadPackage(eventListener);

            // Loaded
            Console.WriteLine(string.Format("> state: {0}", pi.State));
            // Package.dtsx
            Console.WriteLine(string.Format("> name:  {0}", pi.StreamName));

            // Now what?

            // Cannot convert type 'Microsoft.SqlServer.Dts.Runtime.PackageItem' 
            // to 'Microsoft.SqlServer.Dts.Runtime.Package' via a reference conversion, 
            //boxing conversion, unboxing conversion, wrapping conversion, or null type conversion
            //pkg = proj.PackageItems[packageName] as Package;


            // package has parameters as does the project
            // $Package::PackageParam
            // $Project::ProjectParameter

            // All the same work but now with a package that has a project parameter
            packagePath = @"C:\sandbox\so_31812951\so_31812951\Package.dtsx";
            pkg = app.LoadPackage(packagePath, eventListener);

            // The parameter "ProjectParameter" cannot be found. 
            // This error occurs when an attempt to retrieve a parameter from a 
            // parameters collection and the parameter is not there.
            // pkg.Parameters["ProjectParameter"].Value = 10;



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

    }
}