Remote starter option tweak

I have 2010/III model with a remote starter option.

I am planning to build a small enclosure and put a micro controller (Arduino) connected to a keyfob lock button, all enclosed. It will display time and some knobs to set it up. Then, at selected time, it will "press" lock button three times and start the car cooling cycle (and keep the car locked). That way I can program it, sort of as an alarm, to when I will be back to the car, and the car will wait for me air-conditioned.

My question is, would it be possible to buy a key fob on the secondary market and have it program so that it only locks the door, and not be able to start the car?

Also, would that even work? I have SKS and with the smart key I am able to do it from inside the car, but would a simple key be able to do it from the inside? (Is turning on the a/c a function of lock-door signal pressed 3 times, or it still requires sort of secondary authentication for the engine start)?

thanks!