You can get to it and unplug it by removing the front right dash speaker cover, and you will see it. I don't think you can actually remove it through there though, may have to take off some extra parts for that.
I installed an aftermarket stereo a couple of months ago and have a aftermarket amp. I used the crutchfield wire harness kit, which leaves the OEM amp hooked up. May have something to do with the output voltage (4 instead of 2 that some of the cheaper units had) of stereo I bought, but the whole system sounds clean and cranks.
Thanks for the help, much appreciated...looks like I will have to take the glove compartment door off and a couple more srews...does that speaker cover just pop off??