Hi Andy,
I've just changed the DV on my KO3 GTI last weekend (having taken off/refitted the old one the weekend before to check condition/revision).
Very simple to do if you have a 1/4 inch drive ratchet set with plenty of extension bars, a universal joint if you have one and allen head bits. This is how I approached the job:
1. Slacken O/S/F roadwheel bolts
2. Jack up O/S/F of car and support on an axle stand for safety
3. Remove O/S/F roadwheel
4. Look through the space where the driveshaft passes above the subframe and under the structural wing member (having the bonnet open and a torch is helpful here to light the area). You should be able to see the DV, held into a verticle metal pipe by three allen headed bolts.
5. Remove the single multiplug by pressing the small tab down and pulling off
6. Use your extension bars and universal joint as necessary to remove the three allen headed bolts - DV should now fall away easily.
7. Replace DV (with new or old if just checking) - it will only fit one way due to a small stud that locates in a hole next to one of the bolt holes- and refit the three allen headed bolts with a drop of threadlock (careful not to overtighten!)
8. Refit roadwheel, remove axle stand and lower to ground (remember to torque up the roadwheel bolts and recover your locking nut key!)
As they say, experience is everything and once you havce done it for the first time you will wonder why you worried!
Steve