Interesting update for my own personal situation. My car does not have the heated seat option but I had replaced my seats with heated sport seats (both old and new seats are premium) a few months back.
Taking this one step at a time, I picked up these Heated Seat Buttons
I replaced my button panel which at the moment only contained the PDC button, with the one above, including putting my PDC button back in the same spot its in now (2nd from the left). Results...
Drivers side heated seats...WORK! No VO coding, nothing else, they just plain work.
Passenger side heated seats - do not work, not even the little lights above the button.
PDC still works, no problem.
So, my car appears to have the proper wiring for heated seats, at least for the drivers side. I have no idea why drivers side works and passenger side doesn't but my next step will be to contact Patry's who I understand is the man for this stuff, to have him add the heated seat VO (494?), and hope that addresses the passenger side. If that works, I'm good. If it doesn't, I'm not sure what else to try except the whole Euro retrofit kit but that seems like extreme overkill for what I already appear to have installed.