I had the same problem as you but with my civic. I dont think its that easy simply to add a computer controlled potentiometer and you will have a full climate system. My car had 4 fan speeds and a slider for hot/cold adjustment but I made some hardware and converted it to an automatic climate unit. What I did was use some software to controll the hardware through the usb port and let the hardware take care of the temperature regulation. The good thing about using hardware for this is that if your PC crashes for some reason and you really need to use your climate (demister for eg) it will still operate via a remote.
One question are any of your climate features cable driven or just buttons, send ,me a pic of your climate and I can give you some ideas.