Hi,
I have not actually done anything to do with clutch/gearbox on my golf but i have done of various other cars i have owned in the past...
Basically you want to be looking for a hole in the gearbox casing (usually "bell" shaped) that you can insert a piece of high strength steel in (like a peg - i have used the plain part of a drill bit before). There is a corresponding hole in the flywheel and you will have to find out what position to crank the engine to (by hand) which i imagine will be in the Haynes manual, although its usually "cylinder 1 to TDC". You could do trial and error by getting a mate to gently turn the engine over by hand whilst you gently push whatever you are using as a peg inwards - it will slot in all of a sudden and you have found your hole as it were...
I would recommend putting bright red tape or something around the "peg" once installed so you cannot forget to take it out afterwards. If you try to turn the engine over with the key and the peg is still in it will be bye-bye for various components!
Hope this helps and that VAG engines are not massively weird or different to any others out there
