Some day I plan to do this with my StarVision..
Basically, the power button momentarily closes the circuit underneath it to provide the power through to turn on the screen.
So what has to happen is there needs to be something else (relay from ignition or ITPS or OPUS?) which will momentarily send the signal to that circuit to make it "appear" closed for a sec to turn on the screen.
I think the momentary output from the ITPS is perfect for this. It provides a small burst of power for a second to turn on your computer. It could be wired to the circuit in the power switch of the LCD to do the same thing.
Good luck if you try it.. Let us know how it works!
I'm too scared to try it, and I don't really have time to fiddle with it right now for a few weeks at least..
I don't know if it will work or fry the LCD, so try this at your own risk, but I don't see why not..
If someone does this, I suggest you voltmeter the circuit behind the power switch FIRST and see what voltage comes out when the button is pressed, then wire/solder that up to your ITPS or something and see if you can get it to work.