Found the following over at
http://www.petri.co.il/forums/showthread.php?t=39459
How to Activate 2008 from command line
Open a command windows
slmgr.vbs -ipk "product key"
You should recieve a cscript success message
now run windows\system32\slui.exe
now just follow the normal activation instructions.
Use this to check activation state: slmgr.vbs /dli
