the only problem I see with your setup is how you choose to route the audio from each device to the speakers. As far as hooking up the power, that should be no problem, PS2 will require an inverter, the screen and the headunit should be 12 volts, and should be fused on the positive side. I would wire them separately so you wont overload the fuse for the radio. If your headunit has a line in, which a lot of higher end headunits have you can run the audio from the PS2 to that... If your headunit does not have line in, you'll need some other way of switching from the radio to the ps2, which i'm sure are available, but you'd probably be better off just selling the headunit and buying a new one.. Its better to spend a few more bux and take a little more time and do things the right way the first time, instead of spending double to fix a bandaid later down the road.