I did a similar setup in my X with a PS2. I used a 5" screen and rigged the mounting bracket behind the dash so the mount sticks out of the middle expansion hole on the 2002/2003 dash. I also ran a switch up to the console that controls the inverter. The wires for the PS2 and screen are routed into the glove compartment so the PS2 sits in the glove compartment while in an open position, which is good because it's easy to remove. My wife & I only use it for long trips so we wouldn't want a permanent install.

Here are a few pics of the dash. I can add more if you are wanting to see something specific to the install.

My install (after completed)