With most cars, it's not as easy as swapping the panel. There is quite a bit more to it then that usually. That's not to say these cars are different though, especially since the normal controls are half way there vs being totally mechanical.
Anyways, after having auto climate control in the past, it's not even close to a must have in my book. The only time I really enjoyed it was on long drives during times like the spring and fall where the temp changes are drastic enough to need a/c during the day and heat at night. Was kinda nice to cruise along at a set temp through that. The down side of it was if you were trying to get the best economy, you actually had to play with it more then a manual setup. The auto control, at least with nissan, has the a/c compressor on by default, even if you are only using heat. Therefore every time you started the car, you would have to deselect the a/c every time you started it. Another quirk as far as economy goes is most systems use fresh air setting by default, and only recirc when starting the car. Best economy with a/c on is on max and recirc. In addition to that, starting in recirc is fine during the winter when you want to keep heat in, but not during the summer. The summer just seemed totally backwards. To me, you would want an auto system to start in fresh since the 90 degree air outside is still cooler then the 120 degree air inside, and then switch to recirc after things have cooled down. One last thing I discovered is one set temp doesnt always cut it. Sometimes you want it cooler, sometimes warmer, depending on the sun, what you are wearing, etc. Bottom line is I was fiddling with the auto system much more then I would a manual system, so there really wasnt much point to it.
^^^ I doubt it's plug 'n play because there's probably an extra computer, or just extra programming, needed to use the Auto A/C that normal manual A/C's are lacking. I doubt having just the panel will do much for you.
It is possible to do but you would need sensors and the panel or unit. Some sensors you would need is the photo sensor, heater core sensor, Ambient sensor, the auto motor, and the harness. It is a difficult task since some things you would need to do is hard wire certain parts to the main harness while some wires you just don't need. I did this mod on an Acura Legend a while back and it is a pain to do.