I am not really sure what kind of answer you expect here. Most would probably come the other way and tap the screen signals to send it to encoder to go onto something else (like the DS and 3ds capture stuff) but you could do some kind of component harvest and spec up a new board, and not just for decoration.
There are benefits to parts harvest approach compared to clone chips by whatever means, and there are downsides.
If you are asking this question in this manner you don't really have much hope of doing much any time soon, give or take someone else doing the work and you following a guide or something.