It took about an hour maybe hour and a half to install.
1. remove the visors, the overhead consel, and the a pillars. they all just simply unscrew. the headliner is then free to come down ehough on the front to allow the wires to be run.
2. place template on the roof and tape into place. using a drill begin drilling all the holes that the lights require. (or the 7/8" hole that the light bulb and socket to go through I used a regular old hole saw). It worked perfectly.
3. install lights into the roof and run wiring. for the ground I wired it to the metal framework in the ceiling that the overhead consel imounted to. for power I connected to the pigtail plug that is behind the passenger side a pillar.
4. put truck back together and wipe off any shavings that might be anywhere on the truck to keep from it creating little rust spots.
Good luck with the install, it is not hard and it saves you a pretty good chunk of change. If you have anymore questions, ask!
Another advantage I guess to doing it yourself is that you can get a little custom to the location of the lights like I saw a 3rd gen about a month ago that looked to have a dozen lights on the roof. It was a little different, but the owner liked it I guess.