Your going to need the normal RCA plug inputs(red/white/yellow), yellow is your picture and some portable DVD players are only mono so you may only have red OR white....
other than that, get yourself a power invertor(to power the PS/2) and you are good to go, I had a 6.5" In-Dash DVD player that I used to run my PS2 through, was a lot of fun on road trips for my buddies.....