Its quite simple with the proper tools. I can't remember off hand the size, but I think its 10mm. You'll need deep well metric sockets, maybe a short extension for ease of motion, and I also used a ratcheting wrench. There are either one or two long carriage bolt-type shafts that you will just have to unscrew the nuts from. The pain is that the motion of the nut doesn't become free after it is loosened, it remains too tight for hand-loosening all the way until its off. I'm sorry I can't be more specific, its been a long time but this should help you in the mean time if you get online. I'm more or less studying right now but when I go for a cigarette I'll look more closely.
Okay so it has been a while. You still probably want a deep-well socket, but a ratcheting wrench will work well too. It is 10mm. Just one bolt/nut. It is behind the panel in the back side. Once it is loosened the tail light needs a jiggle. on the side opposite to the bolt is a metal retaining clip. Hope this helps!
The pics suck hard. All I had was my iPhone and a flashlight, but I think its enough to help you out.
what do you want to do with the chrome ring? if you want to remove the chrome, at least on my 06 r53 there was red under the chrome, and i removed it with denatured alcohol but BE CAREFUL TO NOT GET IT ON THE
REVERSE LIGHT chrome. it is quick and easy. i read on here that there might be a black trim under the chrome on the earlier models.