Hey man, i am planning to recover my cloth door inserts soon too. I ordered some leather arm rests off of ebay already, and i know they clip on somehow. I am hoping that the cloth door panel part does something similar but i don't know yet.
If we get no answer (i did a search, nothing) then maybe i can post up some results when i get a good look with mine. Although i don't know when i'm going to do that yet (will be when i'm ready to install speakers)
My only other reasonable option is to talk to the upholstery guy who will be doing my seats to see if maybe he can do something with it. I hope i can do it myself tho.