If you want to do the PS2, you need a power inverter.You can get em from anywhere, walmart, etc. Get a dual plug inverter though. You can get the kind that plugs in to the cigarette lighter, OR you can hardwire it in to one of the ignition wires under the steering column. Once you have the inverter in there, its simple, just run your rcas to the right places and your done. Where are you going to mount the Ps2?
If you dont want to use the ps2 I suggest buyin a mobile (12 volt) dvd player. They are pretty cheap these days, you can get em on ebay forl ike $150 or less. You can actually tap into the power behind the radio for this, they dont pull much current. Hope this helps a lil