Yes, a normal/base/limited Alabaster coupe had painted and transplanted a SRT wing on to it's rear hatch. Looked really sweet... too bad the SRT6 didn't come in Alabaster...

On the original thread topic. It could be done, but you'd probably have to aquire the entire rear hatch and then it would be a completely manual switch affair most likely as the speed controlled part is integrated into the body control module (BCM).

Good luck! and... Cheers!