Ok, now that winter is over, I have this figured out.
I set up one of the aux functions on the remote to control a relay. The aux output momentarily powers the relay. The relay then acts as a momentary spst switch.
At the seat heat switch on the drivers door, there are 12 wires coming out. The heat switch in the door closes the contact between the dark blue and dark brown wires. Piggyback these wires to the relay's normally open contacts. Hit the aux button once, the relay mimics the function of the switch and will cause the seat heater to turn on high. Hit the aux again sets the seat to medium and so on. The switch in the door will continue to function normally.
Hope this helps someone else. I spent way too much time on this but will appreciate it next winter....lol