You have to pull the tail lamp assy. Best if you look at the FSM, but here goes from memory.
Open the hatch. Remove the plastic rear cover (this will involve pulling up the carpet, possibly even removing the floor panels in the rear). Wangle the plastic piece out of there, and try not to break it.
You will see a number of screws that hold the entire assy in. Remove them.
While holding the assy in place with your knee, remove the bulbs/connectors from the assy.
Pull assy away from car.
Lay flat on a piece of cardboard. You will see some more screws that hold the trim pieces on. Remove them. Trim will seperate.