Yep, you can connect it to a standalone screen via an RCA cable. A 3-way one like the one that comes with the PS2 will be fine. There's usually a red and white (right and left audio), and yellow (video). If you want the audio to come out of the headunit, you plug the red and white connectors into the aux-in on the headunit, and switch the headunit source to "aux", and then the yellow one goes straight to the screen for the video signal.
The most critical thing though, is ensuring that the PS2 will either run from a 12V supply, or you put a 240V supply into the car. The former can be done by buying a new power supply from the likes of Big Cat Technologies (www.bigcattech.com IIRC) - this is the most expensive, but ideal solution. RRP was £90 last time I checked, although you can pick them up cheaper elsewhere. The other alternative is a 12V-240V inverter, which can be cheaper, but there are issues with these such as heat/potential for fire.
Also bear in mind that the power button for the PS2 is on the PS2 itself, so you need to have it accessible from the front of the car really .. or Big Cat Technologies do a remote power up button - again, quite an expensive option.
HTH
Mark
The most critical thing though, is ensuring that the PS2 will either run from a 12V supply, or you put a 240V supply into the car. The former can be done by buying a new power supply from the likes of Big Cat Technologies (www.bigcattech.com IIRC) - this is the most expensive, but ideal solution. RRP was £90 last time I checked, although you can pick them up cheaper elsewhere. The other alternative is a 12V-240V inverter, which can be cheaper, but there are issues with these such as heat/potential for fire.
Also bear in mind that the power button for the PS2 is on the PS2 itself, so you need to have it accessible from the front of the car really .. or Big Cat Technologies do a remote power up button - again, quite an expensive option.
HTH
Mark