
This one reminds me of [sprite_tm]s keyboard light mod. [Jeff] modded a usb bluetooth module and mounted it internally on his tablet. He connected a small circuit to two the the stock buttons to buffer/de-bounce them to allow simultaneous pressing to activate/deactivate the module. (To add a delicious taste of irony, my bluetooth module was flaking on and off while I read and wrote this up.)
http://www.hackaday.com/2007/06/18/adding-internal-bluetooth-to-your-tablet-laptop/