Sorry, but Mac users are currently unable to flash the bootloader from a virtual machine. Flashing the bootloader is not strictly necessary to flash the device's OS.
Mac users, you can flash the bootloader using [http://dl.cubieboard.org/software/tools/livesuit/LiveSuit_ForMac.zip LiveSuite for Mac] and following follow the rest of the instructions to flash the bootloader, unfortunately you still need a vm to flash the OS.
This will delete all internal user data (such as installed apps).