lay down on the ground, slide your arms under car, and swear a lot! Or have the neighborhood six year old do it.
I have replaced both of my fog lights and they are a real pain. It works best if you have ramps, which I don't. Last time, I used the floor jack to get more room. The housing rotates about 30 degrees and then can be pulled off. The biggest problem is that the wiring is always in the way and you really need three hands to get the new bulb into place. Check Fred's TDI, I know that there was a detailed description somewhere. The right backup light is a real joy too! You have to remove part of the under-body panel to get to it.