That seems like much to remove trim. Wow. I would assume that it would just pop off."Per the book"
1) Lower the movable rear window all the way
2) remove the rear door inner trim panel (several more steps to do this)
3) remove a screw that holds the door outer weatherstrip and remove the weatherstrip (that outer lower seal against the glass that has the silver piece on your car)
4) remove the rear door frame weatherstrip (the big seal around the top)
5) remove 2 clips and remove the rear door frame trim panel
6) remove 3 screws and the rear door frame finisher (silver part across the top on your door)
7) pull the movable window weatherstrip loose
8) pull off the fixed window outer finisher that you want to replace
Reassemble in reverse order after installing the new piece.