For anyone who is interested, I've created a Vagrant-based VM configuration that you can run and get a easy to use virtual machine to do your building on. The current configuration sets up the apt configuration and installs the binary packages as recommended on the wiki, and FRCMake seems to work correctly.
It's an Ubuntu 12.04 image, but the binaries seem to work just fine there. I've built the core of RobotPy with it, and the build succeeded without any problems -- though, I haven't ran it on the cRio yet.
Get it from
the github repo.