Grey_04_RX8

The time has come for me to sell my other car (98 Mitsubishi Eclipse) but i wanted to put the subs from that car into my 04 RX8...i've been ready some of the postings and i can see that most people are just hooking their subs and wires into the stock HU...i was wondering if somebody would be willing to explain to me how they did this because i don't want to just start taking things apart before i know what needs to be done....