If the power is available at the seat, then you might be able to as most cars without these options are typically pre-wired for them. However, having said this, it might be quite expensive to add them in after the fact..
I'm not sure. I think it's hard. I've been trying to do research on this, & coming with all sorts of dead ends. I think it's on the I-bus, and that's how the signal gets from the HVAC faceplate to the seat. You'd need 4 heating elements, and a connector into the seat harness, and a new faceplate. I wonder if you have to tell Tech II that there's heated seats in the system (probably since it's a Profiler setting in the SID).
I could just be making it complicated, but I think this is an advanced head-scratcher. I know there's at least 1 member here who's pursuing it, but he may be out for awhile. Course I haven't actually asked a dealer yet...I have a feeling they'd just laugh.