Seeing as how you have a Malibu, the above isn't really going to apply to you
Yours is installed from inside the car, and is held in by small sheetmetal screws and retaining clips. You will need to remove the interior trim in the area.Typically, you will remove the rear seat cushion and backrest, sail panel trim, lower quarter panel trim, and B pillar trim to gain access to the window area. They are usually quite brittle by now, unless the car spent most of it's time away from sunlight.You should be able to see the clips at that point.
The advice on butyl tape is correct, and it is sealed with butyl as assembled by GM. It will require moderate to heavy pressure to break it free.
The belt molding's retaining screws will be visible once the glass has been removed from the car.
Here's an offsite link that has some pics in it....it is how to convert to standard qtr windows from Landau, but the removal process is the same.
http://www.maliburacing.com/forum/viewtopic.php?f=19&t=100423
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