Just a FYI..
The first time that I cleaned was about 3 years ago and I just taped round the lamps and buffed in place. This past weekend I actually took the head lamps out when I cleaned. For my 04 e60 it was very easy to take out. Just two torque screws on top and then just loosen two torque screws at bottom of lamp's backside.
I also had to change a burned out angel lamp.