rmaybach,
I wired mine kind of ghetto, but it works. All the stereo wiring on mine is behind the passenger kick panel. I spliced into the rear channels to get the signal for the amp. I then wired power directly from the battery with the fuse that came with the amp in-line "floating" on the wire. The negative from the amp goes into an accessory circuit in the fuse box. I also put an on/off switch on the negative cable. So my subs think they are both rear speakers now. It works pretty well. I can control bass with the bass level, fade, or turn it off completely with the switch.
Good luck!
