To remove the rear quarter glass, you need to remove C-pillar and D-pillar trim panels. After that's done, remove the rear quarter trim panel.
Then:
2. CAUTION: To prevent damage to the coat hanger retainer, use a 3/16-inch flat-blade screwdriver for this step.
Remove the front and rear coat hooks and lower the headliner over the rear quarter window glass.
-Open the access cover.
-Insert a screwdriver into the coat hook slot and turn the screwdriver 90 degrees so that it engages in the plastic component slot. This will spread the steal attachment clip wings to allow the plastic component to disengage.
Vehicles with power vent window
3. Remove the bolts and rear quarter window regulator motor.
-Disconnect the electrical connector.
-Disconnect the rear quarter window regulator.
All vehicles
5. Disconnect the audio antenna.
6. If equipped, remove the air duct.
-Remove the pin-type retainer.
7. CAUTION: Have an assistant hold the rear quarter window glass.
-Remove the rear quarter window glass.
a.Remove the nuts.
b.Remove the rear quarter window glass.
8. Remove the excess foam butyl from the window opening.
To reinstall the glass, you're going to need some butyl foam.
It seems pretty involved. Why are you replacing the rear trim piece? I can't seem to find a way to take off the D-Pillar moulding, all I can find is the part number for it.