Sorry I do not know the in depth details involved. Here is what I do know and what I decided to do when I thought about this years ago.
The auto and manual cars have two completely different ECU's. I looked into this several years ago on a 13 GHIG premium. You must swap the manual shift ECU for an automatic ECU of the same year and I believe they may both need to be premium or standard package units as well due to the instrument cluster. Then once that is complete you have to get the new ECU to communicate and recognize every other CANBUS network module in the car and vice versa. It's not a walk in the park like the old days of swapping a T5 for a C4 in a foxbody.
I ended up putting the 13 back to stock, trading it for a 14 GT premium auto at a great price, put the 2300TVS package from the 13 and other mods on it and never looked back.
After speaking to my buddy who owns a speed shop and has done this for people, or at least helped them with the ECU portion and coms after they do the mechanical swap, I decided against it. The cost doing the mechanical myself and having him do the ECU and CANBUS side and factoring the time involved just did not make it worth it for me. Hats off to those who have done this. But again its not just a mechanical swap and go.
