Couple of thoughts. I would worry about the heating element burning through the cloth cover. To that end, I would hope you got a heating element meant for cloth seats instead of leather. OK, public service message over. By the way, if you want to take a look if there are differences, the VW Jetta, vintage 2000-2005 for instance, have a cloth seat option with heated seats. The heated seat switches are above the radio if you try to find one.
I just installed the harness and leather seats in my 01 XJ. I took the entire harness out of several cars now as my first one I cut up since I wasn't careful and unfamiliar. I also have a 98 Harness that has the power seat only on one side.
My 01 harness has a blue and red plug that goes to heated seat switches. It is tied into the main harness for the two seats which is a complete system tying into two prong electrical plug on the passenger side, coming out of the side of the rocker panel where the wiring is placed.
I also have a cut up harness that you could have as I cut the heated seat switches there, but can splice it back together.