I had trouble getting mine back on my '83 SD's driver side door. I had trouble getting to the Philips screw that secures the front of the armrest to the door.
As to that trim plate, are you talking about the black thin plastic piece? If so, a small flat blade screwdriver will pry it *out*; then I think you can remove it after this is off. Not sure if this is what you want to do... my own personal experience would advise caution and if you're struggling too much with the thing, take it to a tech who's done many of them. My personal frustration involved breaking a seat switch trying to force the door panel on, this after successfully de-soldering the old one, adding the upgrade kit for the seat switch (just soldering, but space is a bit tight). It worked perfectly, until I broke it forcing the door panel back on
[This message has been edited by Robert W. Roe (edited 10-09-1999).]