I had the dealer put an autostart into my SEL V-6 before I took delivery. He charged $325 installed, and took care of the 'intellignet key' problem. Works like a charm, from up to 75 feet away.
I did not opt for the version with extra goodies since the Fusion has all it needs for remote entry. The booklet with the remote start says it can send a pulse when energized, which means I can wire it to start the rear defrost, front defrost, seat heater, or whatever. I haven't attacked that option yet.
BTW the remote start is an additional little pushbutton thingie which is on my keychain. If I thought $325 was a lot, we've had cold weather, snow, and a lot of crap here and everytime I can just go to the window and push a button it is worth $325 to see the green envy on the faces of my coworkers who have to go outside and warm up their cars.
I also put one on my '96 Contour, but did it myself. It cost about $200 and it was one hell of a job, required extra parts ( a Radio Shack box and a switch) to have summer/winter control, etc. For the extra bucks, let the dealer do it!