These two files (DigiKeyboard.h and usbconfig.h) replace the original digikeyboard files in the following windows directory. %localappdata%\Arduino15\packages\digistump\hardware\avr\1.6.7\libraries\DigisparkKeyboard (please note that the path may change for different versions of the digistump files and Arduino IDE)

%localappdata% is the environmental variable to take you to your user's local appdata so the path will work.

Once these files have been replaced, recompile your existing code to your digispark and you will be able to use the same script to run your keyboard commands within a system BIOS)