remove third brake light if so equipped.
remove seat side bolsters by removing bolt at bottom (easiest done with rear seat bottom out, two tabs up front, pull and pull seat up and out), lift bolster up and away.
Its been awhile, so my memory is a little fuzzy, so you may have to remove some plastic trim around the c-pilar, jimmy with the shoulder belt and pull the panel out.
Also do a search on this one. You're not the first to ask.
when i did mine, i pretty much had to rip it apart to get it out, there are little pastic tabs that you have to push in the center, then pry up, i had to cut the hole for the seatbelt to get that out, didnt want to remove the hole seatbelt assembly.
what are you making the new deck out of? and what do you plan to use to hold it down?
I used 3/4" MDF and secured it with those big as ancor bolts, solve the rattling problem with the rear!:lol: