Where are you trying to mount the lights on the roof? If close to your windshield, you're gonna be in for it.
From my experience, mounting lights that close to the windshield just causes too much light to be allowed into the windshield, washing everything out.
I plan on making some kind of light bar that goes slightly infront of the windshield, almost like a Heeps, to keep the light off the windshield.
As [MENTION=94545]MTD[/MENTION] said, running lights through the roof is a time consuming process, and you're going to need more wire.
So far, I have 5 of my planned 9 lights mounted on my roof. I think I used about 12' for the front, and about 20' for the back, for both power and ground. For just one light/set. That was (1) 6x9 KC long range, (2) Hella 6",both on the front of my roof rack, and (2) 4x6" Baja brand lights on the back of the rack.
I wired the 6x9 by itself because of the power, the (2) 6" Hellas together to 1 relay, and the (2) Baja lights together to one relay.
So, I have about 24' of wire for the 6x9, 36' of wire for the two Hellas(power to both lights from the relay, and ground was joined from both lights), and about 60' for the two Bajas(again power for both lights to from (1) relay, and the ground ran in series). The alley lights, I plan on making my own LED ones, and they will be wired in a series. So the amount of power that comes off them is enough to be ran to (1) relay, so about 40' for those.
I ran the 6x9 down hole under the roof rack front foot, and down the driver side a-pillar, the (2) Hellas the same way through the roof, down the passenger side a-pillar.
The alley lights are going to be wired the same way, but from the back foot of the stock rack mount, all the way forward to the passenger a-pillar and the Bajas are ran the same way as the alley lights are.
I did all this wiring while I had my head liner out, which made it a million times easier. The first time I did it, I had to hold the head liner and the plastic trim out of the way, while trying to fish the 6x9 and Hella wires through, then I had to tuck them all under the headliner/trim. PITA.
The length of the harnesses that come with the kit are not long enough to be able to mount it to the roof, so you're going to have to get wire, and make your own harnesses.
Which is NOT hard, just time consuming, as I stated earlier.
I had this massive reply typed out, but then thought, "maybe he knows what he's doing with the wiring, better not insult his intelligence."
If you need help with making your own harness, let me know. I'll be glad to walk you through it.