I think it would be best to check with your dealer. I would assume that if that option wasn't on the build manifest, the wires are not there to support it. Then you would probably need the dealer to flash the BCM to make it work.
My experience is that all the wiring is usually there (definitely for the towing stuff). They only make one wiring harness for these things. The switch is actually on the steering wheel; you'll probably have to buy that, too (I had a loaner once; if I recall, the heater switch is part of the speed control switch group.) You might also have to install a fuse. Be very careful of the air bag.
I am seeing different part numbers for replacement wiring harnesses with and without heated steering wheel, so it will probably be more involved than just replacing the steering wheel. You would need the harness, switch cluster, maybe a relay and a fuse and probably have to get the BCM re-flashed with the new option. I am thinking at least $600 to do yourself and $1,100 to have the dealer do it. Maybe you can find an aftermarket shop to do itfor less than the dealer.
Let us know how you make out. I do use mine on the cold days, I need to turn it off after several minutes as it gets too hot. It would be nice if there were a temp control on it, even just a cycling on/off timer, hmmmmmmmmmm.