Ok, after studying the wiring diagram for a little bit, it looks like it is "possible" to retrofit non-OEM seat heating elements with the OEM switches...i say this loosely since I'm not sure yet what kind of current draw is available vs. what seat heating elements are compatible...plus you'd need two-stage heat.

The 5-pin connector (actually a 6-pin connector with 5-pins) is intended to connect the lower seat heaters (left & right), while each of the 2-pin connectors attach to the left and right back rest heaters. These harnesses (5 pin and 2-pin) seem to be connected to each other in the diagrams even though they appear to be separate under the bench seat.

The backrest heating element needs two wires to connect to two pins. The seat bottom heating elements is a little trickier. Each element has to have a temp sensor in it to monitor heat level. The switches on the console will read the temp to determine when to shutoff/turn on. These pins might be shared by both the left and right seat bottom elements...but i'm not 100% sure, might need someone's help to read it correctly since there are a total of 5-pins available for two elements and temp sensors in each.

Other than that, you would need relay terminal 15, OEM switches, and to get proper mating connectors or rig it so that it will connect to the OEM harnesses under the seat.

Anyone with feedback would be great. I'd hate to get anyone's hopes up by messing up the Wiring Diagram analysis. If this works, it'd be a heck of a lot cheaper than buying new seats!