I seem to remember reading somewhere that the actions board is a mod of the original gameboy board.
So, if your interest is the actions solution, and you know the gameboy specs, you may have a close approximation.
Also if someone has an old game boy floating around, if you can connect it to your 'puter, then run Udisk on it we may have an answer.
Wouldn't be fun to try out firmware mods on an old gameboy so you don't fry your new toy!
We may end up with a new hybrid, maybe the Mboy or Game4?