Two issues: Power and Interface

- You would have to find a way to make the board accept the 5v coming via the USB cable
- You would have to see if Apple cheated on attaching their BT module in the keyboard by using a USB interface or have active pinout for USB to act as an output to a machine.

If you can meet both of these conditions, then you "should" be able to mod it though you would be better off getting a wired keyboard. You could get rechargeable batteries for your keyboard also. Have you looked into using a non-Apple keyboard?

I like the Das Keyboard myself...