I call this Part I, because i will eventually get down to the entire car as I slowly progress to other areas during the installs of aftermarket bliss.
I started off with the rear shelf because that and the front door panels are the most annoying thus far in the rattle dept. Plus I removed the rear shelf plastics so I could get closer to the rear window to install my tint (although it didn't provide me with much extra room].
Disassemble the rear c-pillar trim. The piece closest to the rear window comes out first. The top most corner is held on by a plastic push rivet. Be careful as you pull the front trailing edge, it does just snap in 3/4 of the way into the rear triangle surround plastic, but you have a metal push clip that you will need a flat head to depress the tab to release (unless you have REALLY small hands).
Pop off the bolt cover on the rear triangle glass surround. Using a 10mm socket remove the 3 bolts securing the rest of the c-pillar in place. Gently pull to release the one plastic pin, slide the surround down the seat belt to where it sits safely on the back of the lower rear seatback.
Remove the rear brake light assembly (if you have it). Held on underneath the shelf with two 10mm bolts and a plastic clip toward the rear of the assembly (front of the car). Unhook the wiring harness and remove light.
There are 2 plastic pins holding the rear shelf plastic in at the front left and right corners you need to remove (rear seat back of course has to be down to see and get to these). Gently/firmly pull out and up on the front lip of the plastic shelf to release.
Underneath (from inside the trunk)you will notice 3 accessible WHITE pins. Using a pair of needle nose, gently pinch and push up. There are a total of 5 pins, you can only get to 3 of them.
Gently pull up on the front of the shelf plastic to release the 2 front white pins and you should now be able to maneuver the plastic out off the shelf exposing the wiring for the airbags, brake light, defroster, and keyless module.
**I'll grab some pics of this, I forgot***