2003 Cavalier Amp//Subs/Stock Speaker

Hey, Im setting up a carputer in my car and ive hit the audio part but im not sure how or if this will work at all. Ive got 2 Sony Xplod 10's my front 2 doorpanel stock speakers and my two rear stock speakers and a 760 watt pioneer Amp. Im taking out my stereo and running my PCsound card into the left and right RCA jacks in the amp, but Im not sure how to get the other speakers wired in, Ive only got 4 wire connections from the amp out to speakers. If I wire the 2 subs together and the 2 rear speakers together and the 2 front speakers left and right would that work? And to actually wire them could I run to my old stereo harness and splice into that or will I have to wire directly to the stock speakers. One more questions, Ive searched everywhere but I cant find a stock 2003 cavalier stereo harness wireing diagram =/ Does anyone know the best place to find one?
Any help at all would be greatly appreciated! =)

what your trying to do  won't work well . you need to add an aftermarket H/U which is not very easy in that car the reason for the new H/U is you want to have aux inputs on your H/U so you can run your PCsoundcard into those AUX inputs and then you will have the control you need  if you are going to buy a new H/U for this check out www.ikesound.com you can get a H/U that will suit your needs for about 100 bucks