Amir---
The link I posted above (http://www.fierosails.com/howto.html )
is the most complete, detailed, in-depth instructions I have ever seen on the subject. I could type out my "version" of it, but it would read basically the same as the webpage does, since that's how I do it.
If you are careful, nothing but your fingers, maybe your fingernails, ever touch the paint.
The method that does risk the paint is the one where you remove the inner B-pillar cover, remove the 11mm nut that you will likely drop that is located directly behind the pontiac emblem, and slide the window towards the rear of the car, off the clips. This is also NOT the method outlined in the link above...so that's pretty much moot. (as a side note, I've pulled a bunch like that and have never scratched the paint doing it that way, either.)
If you want, you can even slip some paper between the trailing edge of the quarter window and the paint to protect it, but then you risk sliding the paper around and scratching it. Suppose one could use some material...but, again, if you're careful and follow the instructions on the webpage you don't have to worry about it.
Jeremy B.