First, let me acknowledge that this is not ready for prime-time! I have only tested it with 2GB, 4GB, 16GB & 32GB media, although theoretically, it should work for all bootable media 512MB and larger. It still contains the CrOS kernel from June 2013, because I haven't had time to debug the issues with the updated kernel. At this point, you will need access to another machine running Debian (or Ubuntu or their progeny) or a working ChrUbuntu install on your Chromebook. You'll still need another machine to install a distro on the media anyway, so I gave up on trying to eliminate this requirement.
The archive contains a "ReadMe.txt" with detailed instructions. In the end, you'll feel like you just did 16 cartwheels to move only a meter, but it works. Be aware that everything I have tried to streamline or clarify the process has failed to produce bootable media, so substitutions or shortcuts of any kind are definitely not recommended. Follow the instructions exactly, and you should end up with a piece of bootable media that you can install a Linux distro on. Without further ado, here's the download:
Once you have bootable media, but before you install a distro on it (Step 10), you can create a backup of the disk with gdiskdump (included) and then restore it to this condition easily in the future. Once a distro is running from USB, moving it to the HDD or SSD (say to to replace ChrUbuntu) is a relatively simple task.