Cowtown - The kit I used is from Innovative Heat. 1-800-396-4316. I found it on e-bay for $147 including shipping. It's exactly the same as what I saw on a site for Universal Seat Heater Kit for ~$185. The instructions say it is a Heizgerat Setzt II with illuminated switch...
I just installed the kit on Sunday and tested it out today. Does a nice job of heating up my buns. We've had heated seats in 2 cars before and this works as well as those did.
The install was not as bad as I thought it might be. I didn't have to remove the upholstery at all. I found there was enough room to slide the heating elements in from the back of the seat & the bottom of the back. I opened up the upholstery at the back where the bottom and back come together. I cut a couple of wedges (like a door stop) from wood and covered them with duct tape so they wouldn't catch & snag on anything. Being that the elements are basically cloth with a wire mesh inside, you cannot "push" them in place inbetween the foam and the fabric/leather. I solved that by applying duct tape over the far end and making a pocket at each corner (small piece of duct tape applied sticky side to sticky side so there's no adheasive in that small area. I then used a heavy gauge wire (mechanics wire) with the end bent over so it was blunt and wrapped it with a small piece of duct tape. I could then "push" the heating element inbetween the foam and fabric using the wires. It worked perfectly! Once in place, I could pull out the wires and re-attach the upholstery where it hooks over the ends.
I considered buying the factory switches as discussed in this thread, but decided to just use the ones that came with the kit. The mounting location I selected was on the console right next to the smaller cup holder. They're wasn't enough room to put them side by side, so I put them front to back. I think it looks natural, not much like an add on (unless someone knows of the '07 switch location). I'd put a picture of it on here, but I haven't quite figured that out (always says my file is too large). If you want a picture, send a PM to me and I'll send you one.
Hopes this helps someone out there as I've spent a lot of time putting this in ;>).