+Moritz Ulrich its connected to usb? did you have to add the usb cable too? this is interesting, because if it comes with usb cable, then one can buy this and use it like a extra functional keypad. Or did you went great hacking to add the light and usb?
if the unit comes with usb and can work as extra function keys (one question remain, what scancode these key send, or whether it's possible to set in firmware, how easy), then i might write about this along with the pic to a page i have on extra function keypads.
but otherwise, if it requires hardware hacking skills as you've done, that's worth writing about too i think, as there are several details.
It comes without any electronics (just the switches). Making it a real keyboard isn't that hard, but it's some hardware-hacking doable with a soldering iron and a Teensy or Arduino microcontroller. Using an Arduino, you can fully program it and make it send whatever scancodes you want.
+Moritz Ulrich i put on my site. Thanks! if you do write up on how to, that'd be great. As i think this kit about $20, with 6 keys. Far cheaper than other packaged solutions that's $60 to over $100 for extra function keys.