Aight, this is what you gotta do. First go here
http://www.audio-warehouse.com/detail.asp?mdl=PLXR2 and buy yourself some of this line out converters, so you can hook up the PREAMP RCA's to your STOCK head unit. Then you run the remote wire from the amp to a switch you need to fashion up front somewhere, and wire the power from the switch off the ignition. Thats pretty much all you have to do, personally it'd be a lot easier, and higher quality, get a aftermarket head unit and a wiring harness.