I don't know the specifics, but the dome lights are hooked up to a funky circuit... you might have noticed that the lights slowly fade away when you shut the doors. Just about everything that seems simple is pretty complicated in these cars, ie: door locks, power windows, dome lights... etc. I've never took the dome light assembly off, but going to the bulb, there has to be only two wires. The switch inside the assembly would be the most complicated part. Like many other circuits in cars, the dome lights are probably negatively triggered, so you might have to run two wires straight off the dome light bulb since the ground off the bulb might be isolated from the actual chassis ground. Even though neon lights don't take much energy, I would still suggest using a relay to ensure that you don't blow a fuse.
Back to the subject of all the complicated circuits in the car, has anyone ever played around with the window lock button on the driver's door panel? Very intersting the way it works...
When it's locked:
1) no one can control their windows, but I can.
2) If the front passenger is pushing the 'down' button, I (driver) cannot roll his window up.
3) If the rear left passenger is pressing his 'down' button, the front passenger is pressing his 'down' button, I can *slowly* roll the front passenger's window up.
There's probably some other weird combinations, but I was doing this on a real warm day in the BK drive-thru and I wanted to roll up all the windows and turn the heat way up to piss off my friends in the car. :p