The documentation for GenericHID can be found in the wiki.
On Ubuntu, this command will installed the required build packages. There is a total of about 200MB on a fresh system.
sudo apt-get install build-essential qt4-qmake libqt4-dev libusb-1.0-0-dev gcc-avr binutils-avr gdb-avr avr-libc avrdude
Note - GenericHID still uses qt4. If you have qt5 installed on your machine run qmake-qt4 instead of qmake below. If you have already run qmake for qt5, it is easiest to retreive a new clone of the repository and start again.
> qmake
> make
> sudo make install
A windows build is currently not supported until I decide what to do with libusb. libusb-0.1-win32 does not support Win7+. libusb-1.0-win32 has some significant differences to the linux version to make it work. It also doesn't support running as a general usb access library anymore either.
The firmware is now part of the build. 3 versions are built and put in the bin directory: usbkey.hex (at90usb1287@8MHz), generic16.hex (at90usb1287@16MHz) and teensypp2 (at90usb1286@16Mhz using the half-kay bootloader).