Backup Mac from a Live CD

"Why don't you just boot into the OS X install DVD and when you go to install OS X, select ""Archive and Install""?

It gets even better if you are using Snow Leopard! Just boot into the Snow Leopard installer DVD and install Snow Leopard over the top of your FUBARd OS X install. It will not delete or remove any of your personal files (both your home folder AND /Applications/), but it will fix and system files you have removed or screwed up. I had been mucking around with the language files (changing every string in Finder to ""LOL""), and forgot to make a backup. To fix it, I just reinstalled Snow Leopard over the top and everything was fine. It was as if I had never made my silly modifications.

If you are not already running Snow Leopard, I would strongly recommend you take advantage of your situation and upgrade to Snow Leopard now. The install process is a whole lot more efficient and should work better, especially in regard to disk space.

If you need to, you can actually use your OS X install DVD to backup all your important files:

From the installation DVD, select Terminal from the Utilities menu at the top of the screen.
Once in Terminal, run ls /Volumes to see a list of all the mounted drives. Take note of the drive of your OS X install. Mine is ""Macintosh HD"".
Run cd /Volumes/<OSX VOLUME>/Users/<USERNAME> in Terminal to navigate to your home folder. Remember to replace <OSX VOLUME> and <USERNAME> with their actual values, and put a forward slash (/) before any space. If it is easier, you can hit tab to automaticly complete the folder names (after typing a bit of it out.
My full command would look like this:

cd /Volumes/Macintosh\ HD/Users/joshhunt/

Now, using the mv command to move folders and files (such as your VMs) into you home directory. For more information on how to use mv, see it's man page
Close Terminal and continue the installation."