The value you need is the user SID. This WScript will get the SID for a specified user:
strComputer = "."
strUsername = "username"
Set objWMIService = GetObject("winmgmts:\\" & strComputer & "\root\cimv2")
Set objAccount = objWMIService.Get _
("Win32_UserAccount.Name='" & strUsername & "',Domain='atl-ws-01'")
Wscript.Echo objAccount.SID
To get the username:
Set wshNetwork = CreateObject("WScript.Network")
strUser = wshNetwork.Username
good luck!