http://www.joeware.net/freetools/tools/auth/index.htm

Auth V01.01.00cpp Joe Richards (joe@joeware.net) August 2001

Usage: Auth.exe /d:dom /u:uid /p:pwd

The wsus server URL will be in the windows update log c:\windows\windowsupdate.log

or

HKLM\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\WUServer