Hi,

thanks for reporting. We don't consider Mac OS to be supported by grml2usb, since - at least to our knowledge 
- syslinux/GRUB aren't available in according versions there and just getting the mbr stuff to compile would 
be just the start to support grml2usb on Mac OS.

If someone has patches for grml2usb to get it working on Mac OS I'd be happy to discuss this. But for now no 
one in our team cares to write them, so closing this bug report with won't fix.

regards,
Mika