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.
Position the rear window all the way down.
Remove the outer belt sealing strip screw.
Fig 1: View Of Outer Belt Sealing Strip Screw
Courtesy of GENERAL MOTORS CORP.
Pull the outer belt sealing strip from the rear door pinchweld flange.