While not impossible, its pretty close.
The heated seat setup kinda sorta "talks" to the BCM and reports how much current it is using, etc. The circuitry for that is not necessarily built into an aftermarket set (in fact it most likely is NOT built into aftermarket sets). The aftermarket sets kinda sorta "talk" to their own box which will shut down the seats if necessary.
Best bet if you want factory setup is to buy a used set of heated seats, Big Horns could get cloth heated seats which are generally the cheapest way to do it. You could go whole hog and buy a set of leather heated (and maybe even vented too), but those are expensive.
Depending on your trim level the wiring may already be there, you would just need to enable the features in the BCM (see the AlfaOBD thread)
Oddly enough, for front seat heaters, the hard buttons are NOT required if you have the 8.4 radio since the controls show up on screen as well.
I added factory heated seats to the front of my Big Horn...bought a good set of used cloth heated seats and installed my own Katzkin leather kit. On the rear seats I went aftermarket (while I was installing the rear leathers) and mounted the switches in the lower pillar panels next to the seats. They dont look as nice as factory, but where they are located they are covered by the seatbelts unless the seat is in use, so I dont really see them much
