I cloned the Crazyradio repository with 'hg clone', then fired up an Ubuntu 12.10 VM and installed the 'Small Device C Compiler':
sudo apt-get install sdcc
Performing a 'make' in crazyradio-firmware/firmware resulted in a binary: bin/cradio.bin .
I could have burned this image via SPI, but I have another Linux machine handy (a neat little Olimex OLinuXino with Python already installed), so I cloned the repository on that machine as well, copied over cradio.bin, and followed the instructions on the Crazyradio Wiki.
This flashed the latest Crazyradio code onto my device - and testing out on my MacBook Pro, it did indeed solve the "IOUSBFamily was not able to enumerate a device" issue!