I have the windshield KC installed... Now I dont know if this is the BEST way to do it, but this is what I did:
Flip the windshield down. You will notice that there is a hole in the frame on the driver side (where the wiper wires come through). For the driver side, pass the ligh wires through there down behind the dash. Run the wires to the side of the Jeep (if you take the wires to the front, water will leak in when driving in rain; dont ask how I know!). On the passanger side, there is no hole, so I made one with a drill and followed the same procedure. I used a rubber grommet on the hole (also it is recommended that you paint it to avoid rust), then used a bit of silicone to seal the sides in case you have sideway rain when parked (trust me, water can get in this way; again, dont ask how I know!).
I then took out the rubber plug from the main loom of wires going out to the engine compartment, passed the wires through here, put new electrical tape around the loom, and reinstalled the rubber plug.
The bad side of doing it like this is that you have wires with high amperage behind the dash, which is a potential for a fire hazard, but given the position of the lights, it was the best way I could figure out how to install them there (the wires simply HAD to go in to the cab).
Felipe