Depends on how comfortable you are with your car. When I installed mine on my '86 RX-7, it took about 2 hours, which included installing the actuators in the doors and all the wiring. Also will depend on the car. The doors are really easy to work on in the RX-7, but newer cars tend to have a lot of crap and wiring in there...
like i said before, i have a '94 Pontiac Gran Prix. and how comfortable am i? lets just say i wouldnt mind taking apart the engine to tighten a screw on the oil pan
I don't know anything about the Grand Am, but since it is a newer car, figure there will be some hassle.
Maybe the question "how comfortable" is a bad one. A better one might be "how knowledgable". I know a lot of very comfortable mechanics that don't know a damn thing...