Installing a Head Unit, With Factory Amp Options

[1995GT]

This is my first time attemping something like this. I have the harness and a friend to help. But can anyone tell me how to access the wires with the factory amp? What panels do I have to remove and what do I do about the wires with the factory amp? Any help would be greatly appreciated, especially a how-to step-by-step article.
Thanks
Steve

[Guest_Matthew_*]

I have a 98 GT with the premium factory system and all I had to do to access the factory plug is pull of the trim around the radio and shifter. if you take out the stock radio completely you can access the plug pretty easily.

I ended up not using the factory harness because I couldnt find one so I just ran 12 guage wire from the 4 channel aftermarket amp to all the speakers. sounds way better than the 18 guage wimpy toyota wire.