Below, the steps of the development of the prototype. The list will be updated.
1 - Erase the chip and upload the LUFA bootloader -> DONE
2 - Make the board to be recognized as a HID device (keyboard and mouse)
3 - Create the program for manage keys
4 - Create the user config tool (surely the harder part for me)
5 - Test the proto in real environement
5 - Don't forget to eat cookies
1 - I successfully (but not easily) replaced default bootloader by the LUFA DFU bootloader. I am using Atmel studio 6 with LUFA extension.
Next step soon...