It's pretty straightforward to do with VCDS.
http://forums.tdiclub.com/showthread.php?t=26751&highlight=Instruments
However using a cable you got off Ebay suggests your software may not be 100% legit. A case of caveat emptor it would seem. Maybe if you posted this in the OBD forum someone with a genuine VCSD cable (VAG-COM) could sort it for you.
This is worth a read as well.
http://forums.tdiclub.com/showthread.php?t=223979