Haven't done lights, myself, but this is how I got my garmin antenna wired to the roof.
With the hood open, you'll want to run your wires up the windshield weatherstrip. You can actually tuck it under the rubber flap with something similar to a credit card (soft bondo spreaders work well). Once you get to the top of the windshield you'll run it under the roof trim (called a mohican strip in the auto-manufacturing business if anybody is interested). Then I'd say the next move would be to pull the wire out from under the mohican strip, INSIDE the front roof rack plastic (these should be removable somehow, on every other truck I've worked with it's how you remove the racks or install Thule/Yakima type stuff). Then run it inside the roof rails to wherever your lightbar is.
If this works let me know. I've been thinking it through, if it does work I'll probably do it myself.
