break out the muti meter foo, and start checking wires on the back of the deck, to find ur speaker wires use a nine volt battery and tap the suspected wires to either post when you find one the speaker with make some static use the two rear speakers, and attach a line output converter to them, then you can plug the rca's into the line output converter(best buy part no#auloc) then just find an accessory wire from the radio to run as the remote wire for the amp, then you will need a wiring kit for the amp, make sure to run ur rca's far away from the power wire from the battery or you will get static interferance in you sub then ground it plug it in and set your levels on the amp