Rolo I think this is what you are looking for. Very useful information included here. The LCD controller circuit is key. However, as the article states, manufacturers are not following any kind of convention. Every one does their own thing so it get really difficult. So, what you need to do is find a panel controller that offers the mirror feature you want to use and then find out what sets use it. The easiest way would be to call the controller manufacturer and ask them which panels carry that controller that has the feature you want. Since the article mentions the Sharp LH79520, I would start there. You know who this is, so get some sleep! LOL
Sharp: TFT LCD Interface Signals
Sharp: TFT LCD Interface Signals