sorry but it can't be done with the factory rmst system. I thoroughly looked into it back in early 09 when I got my truck and the 6-button fob system. For 09/10, the heated seats are tied into the can-bus data network system and you would need an interface module to tie into that network but nobody makes one. We even found the heated seat switch wires in the harness and tapped into them but it didn't work. On the 04-08 F150's, you could make it work by tapping into the heated seat switch wires.
as Rambo mentioned, the new 2011 systems are supposed to be able to turn on heated or cooled seats and also rear defrost automatically but I'm not sure quite how? The new systems are on the 2011 Superduty already and I looked in their owner's manual and I don't see anything mentioned about turning on heated seats. I also noticed that we might not be able to install the factory systems ourselves anymore, or at least get them to work. the 2011 Superduty rmst installation instructions show that the rmst brain unit easily plugs right into the truck (without having to splice any wires) but then it shows that the truck's computer/ecu has to be programmed by the dealer for rmst to actually work.
Last edited by SteveVFX4; 09-27-2010 at 06:05 PM.