(12-02-2016, 08:40 AM)Adrift Wrote: That would be fantastic. That's the main reason why I could never get a keyboard so small, the loss of buttons I probably still want/need to use.

If you build your own keyboard based on Teensy or cheap Pro Micro clone it's implemented in TMK firmware which everyone is using. But there is no software implementation for Linux alone.
You can also use Arduino + USB Host Shield and program it with the same firmware, Hasu from Geekhack is also selling little converters which you can program.