WARNING: This page is about a different car, the 2006 Pontiac Montana SV6, 2006 Chevrolet Uplander, and 2006 Buick Terraza. However, it is still accessible from the selected car via links, so may be relevant.
Open the liftgate.
Fig 1: Removing/Installing Liftgate Body Side Wedge
Courtesy of GENERAL MOTORS CORP.
Remove screws (1) from liftgate striker (2).
Remove liftgate striker and rear stowage compartment bracket (3) from the rear floor.