WARNING: This page is about a different car, the 2002 GMC Safari and 2002 Chevrolet Astro. However, it is still accessible from the selected car via links, so may be relevant.
Remove the lace.
Use J 38778 in order to remove the trim panel.
Fig 1: Removing & Installing Rear Door (E54) Trim Panel Lace
Courtesy of GENERAL MOTORS CORP.
Fig 2: Removing & Installing Rear Door (E54) Trim Panel