WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: View Of Rear Storage Compartment (Rendezvous)
Courtesy of GENERAL MOTORS CORP.
Open the lift gate.
Open the rear compartment storage lid.
Remove the seat anchor nuts from the rear storage compartment.