Call PowerShell thru a Web Service

Using Windows 2008 I'm trying to use WebServices andAD.

I can't figure out how to call Powershell thru a WebService. I'm looking for something like the VB code below. Add a reference to the project then make a call. But I can figure out how to get the refence etc.

PrivateSub Call_Web_Service_Method()
Dim CallWebService asNew ServerName.WebServiceName()
Dim sGetValue asString = CallWebService.MethodName()
    Label1.Text = sGetValue
EndSub