Arduino Leonardo/Micro bootloader

I need a boot loader that works with the ATmega32U4 micro controller found on the Arduino Micro and Leonardo boards. The change from the standard Catarina/LUFA boot loader is so that the ATmega32U4 will run from the Internal 8MHz RC oscillator and also be able to communicate and have software (sketches) uploaded via USB in the Low-Speed configuration (1.5MHz). I can currently set the fuses on the chip to select the internal RC and have verified that the board is working at the correct speed and can have code uploaded via the ISP connection.... But trying to upload via USB causes failure. As far as I can see, the Caterina/LUFA boot loader (.hex file) needs to be recompiled/built after making a few minor changes to the source code. The source code and a 'make' file (which also requires a minor tweak) are supplied with the Arduino App, but I do not know how to use this on a Mac computer... I think a windows environment is required. For someone who knows this board/microcontroller I can't see why this is more than a few minutes work.... if the boot loader has not already been created!!!! Please note: Although the boot loader is destined to reside on my own PCB which has no external clock/crystal, I have a Leonardo board to run additional tests on. Burning the boot loader will be vis the ISP pins from and Arduino Uno coded as an ISP programmer.... very simple, but works very well.