OK-you will have to pull the door panels to change the speakers. While you have them off,run new speaker wire back into the car(16 guage minimum but 14ga is better). Run the speaker wire to the location you are going to install the amp. You'll need a power wire feed direct from the battery(remember to put a fuse within 12 inches of the battery). Since you are planning on adding a 2nd amp later,run 8 guage. That size will allow enough current flow for the 2 amps combined,providing you stick to the power ratings you said. Then run 3 sets of RCA's from the deck. Mark the front and rear and plug those into the amp,tape off the 3rd rca so it doesn't short out on something. Run an 8 ga ground to the BODY,not the side of the trunk or an existing bolt used for something else. If you don't ground the amp right you will choke back the power output and possibly induce noise(alternator whine). Also,while you are running the rca's,tape a small 18ga wire from the deck amp-turn-on wire(blue w/white trace) to one of the rca's and connect to the remote turn on connector of the amp. Connect the speaker wire(you marked which was which,right?) pay close attention to polarity cause if you get any speakers out of phase you'll kill alot of bass response. Bolt the amp somewhere(back of the back seat works as long as it's mounted low) and you're done.