I did my 1.9 TDi auto box at the weekend. It's straightforward once the black plastic engine guard is removed - this is the fiddliest bit if you haven't got good access underneath... Which I hadn't!
I warmed the engine for 10 minutes (I know it's supposed to be at an exact temp checked with vag com but I don't have the kit for this... Yet!), switched off, then placed a suitable container under the 24mm sump plug on the gearbox underside, removed the plug and let the oil drain. I left it for a good half hour to drain fully and got about 3.5 litres out (the rest remains in the torque converter). I removed the top up plug in the engine bay after breaking the red seal and then undid the drain level plug with an Allen key - this is a couple of inches behind the main sump plug on the TDi.
Once I was happy I had as much oil out as possible, I refitted the 24mm drain plug and got ready to fill up the box. This is quite tricky and I used a clean 1metre section of hose pipe and a funnel to slowly top up the box. I got a mate to keep an eye out underneath and as soon as fluid came out of the top up hole (Allen key bolt mentioned earlier) I replaced the Allen bolt and refitted the topping up plug (must get a new red seal for that!!)
I plan to do the same again this weekend to get the oil even cleaner.
It's not a difficult job at all and you will have it done in an hour easily.