I recently replaced the "death knell" condition in my left front air bag. I purchased an Arnott bag and decided to do the work myself. All I can say is prep, prep, and prep some more. The instructions leave out details of how to actually perform some of the steps, but I was able to work them out.
Here are a few things I did:

1) I had a friend help. 2 people makes it much easier to remove nuts and bolts and to hold parts.

2) purchased PB Blaster penetrating spray
used this on the pinch bolt and lower shock bolt

3) used a 2x4 x 24" to remove the ball joints from the pinch bolt assembly after the pinch bolt was removed
put the 2x4 under each link and tapped it with mallet. This worked better than hitting them directly.

4) used a 4" extension for the ratchet
- worked great on the top 3 bolts under the hood, which attached to the assembly
- used it for other bolts where I could

5) used Permatex white lithium grease (purchased from auto store) on new rubber o-rings and seal between shock and new bag

6) used Permatex threadlocker - red (high strength) for lower shock and pinch bolt, 6 upper shock mounting bolts (purchased from auto store)

7) had a small hydraulic jack that we used to lift up the lower mount fork sides to allow alignment for the lower mount bolt to slide through. Make sure you raise the shock strut only, and not the link the lower mount it attaches to.

8) used a "C" clamp to pull the front suspension ball joints back into the pinch bolt assembly. This worked very nicely.

9) make sure you use a torque wrench

Here is a link to the Audi Air Suspension Document which describes everything you want to know and see about the air suspension system.

http://www.volkspage.net/technik/ssp/ssp/SSP_243.pdf