Force WSUS client update

here is what you would put in a script to force immediate WSUS checkup by client:
--------
net stop wuauserv

REG DELETE "HKLM\Software\Microsoft\Windows\CurrentVersion\WindowsUpdate\Auto Update" /v LastWaitTimeout /f

REG DELETE "HKLM\Software\Microsoft\Windows\CurrentVersion\WindowsUpdate\Auto Update" /v DetectionStartTime /f

Reg Delete "HKLM\Software\Microsoft\Windows\CurrentVersion\WindowsUpdate\Auto Update" /v NextDetectionTime /f

net start wuauserv
-----------
A more lightweight command:
wuauclt /detectnow