Launching a powershell script from vbscript with different credentials

 Finally after many attempts, the line below does what it should.  Now I need to get the correct syntax to run it with alternate credentials.

objShell.Run("%SystemRoot%\system32\WindowsPowerShell\v1.0\powershell.exe -noexit -command\\net\Hartfiles\Install\Software\NewUser\Create2007Mailbox.ps1" + "'" + strCanonicalName + "'" + " " + "'" + strUser + "'")

All I want to do is launch the powershell shell (From a VBS script) as a different user.