Here a link to how you do it:
http://forums.fourtitude.com/zerothread?id=3756530
But all it really says is:
1. Need two people
2. Remove the three torx bolts on top
3. Remove the plate filler thing, then remove the chrome trim ring by going along the inside edge and popping out the tabs..dont force this...
4. Grip the slats on the bottom of the grill and pull with some force (they will pop out.
5. Have the other person hold the bumper while you pull the grill in the same manner all around
6. On both sides towards the bottom there are 2 stupid plastic screws from the inside out one on each side (this is why Audi says remove the bumper). Stick a long screw driver down there and pop out the screws. (this things is held in be 18 snap things and 3 huge bolts these little PLASTIC screws are over kill and need to go)
7. Get out you new grill and snap it in the the bumper, pressing firmly to ensure all are in all the way
8. Tighten down the 3 torx bolts and BAM you done. This took me and a friend 20 mins total time to do..
Hope this helps
Ashley