You need a 12mm triple square tool to remove the 6 bolts that hold the axle into the transaxle. You need a 17mm hex to break loose the huge stud holding the axle into the hub. A long breaker bar helps a lot.
There is a decent DIY somewhere on the forum on a non-R MKIV. Hopefully someone can post it.
The gist of it:
- Break lug bolts loose
- Jack car up
- Remove wheel
- Break loose 17mm hex bolt holding axle to hub
- Mark position of 3 nuts (16mm?) connecting lower control arm to hub assembly, then remove them
- Remove 6 bolts holding axle to transaxle with 12mm triple square.
- Remove axle
Installation of new is exact opposite. We did not find it necessary to undo the tierod end or the swaybar end link. The axle slid out without it.