Most just do the front i think, to get the back off I am pretty sure you have to remove the whole panel and remove something holding it on from the back side. I could not find a clear answer on a quick search though. Check here for a thread about a broken one. There are some pics that may help, one comment at the bottom says you don't have to remove the panel but no specifics. It can be done though as people have replaced them. It may be like a 2 piece connector or something?? I always thought it was just bolted on from the back. (Mine are still silver)

I did not remove the cupholder piece, just taped around it and sprayed. I did not want to risk messing with the wonky engineering of that thing, I would honestly send to whole part, from my understanding of the process they would only dip it in far enough to cover that section anyway so no biggie if its not removed. Your other option is to leave it out and install the storage bin instead.