I've published my modified version of JoyBorg at GitHub:
https://github.com/voidmapper/JoyBorg

I've added support for dual IBT-2/3 (Infineon BTS7960/BTN7971) H-bridge motor drivers. (IBT-3 support is untested.)

I'm using this for testing while I modify APM:Rover to work with the IBT-2/3 motor drivers.