Ok, I just finished putting my sills in - it took me a while.
I was able to wire both sills to the passenger side.
The first step is to remove fuse #15 from the fuse box. This is the fuse that controls the courtesy lights as well as many other things.
(All passenger side)
First I took the carpet in the footwell. There should be a black piece of plastic with a warning sticker. The plastic is only attached with the nut in the bottom center. Remove that nut and pull the plastic up and out. Now you should see a bunch of wires. The next step is to take out the carpet piece on the right. This is a little more complicated. With the sills off, remove the trim that goes around the door opening. It will just pull off with a little force. Then just pull the carpet piece back/out and then forward/out. I accidently broke one of the clips holding it on, but its not noticeable after reassembly. Ok, now there are a couple of clusters of wires running up the side. Make a small cut in the cluster that looks like electrical tape wound around some wires. The harness you want is tacky on the outside. Once you can see the wires on the inside, locate a brown wire with a single white strip running down its length. This is the door switch ground. Strip a little insulation off the wire and solder the black insulated wire to it. I then taped the joint thoroughly with electrical tape so it wouldn't come in contact with anything else. Next, locate a wire with red insulation and a single white strip down it's length. Strip a little insulation off and solder the joint. Tape this joint as well and then wrap the entire harness where you cut with electrical tape. Then reassemble the car and don't forget to put the fuse back in.
Sorry this is so long, but if I can help with anything else please let me know.