its easy. Depends on the type of lcd you use. vga or composite. Both will run the distance fron the trunk to the dash.
If you use composite, you just run a rca line from your TV out on your video card to the lcd and just run a long vga line if you use vga.
As for power, its a good idea to power it from the computers PSU since thats a clean 12volts. So you just chop off the molex connector and the 12v line is the yellow line and run that to the 12v source on your lcd and then ground it to the black line on the psu. Easy as that.