Hi Mike,
I'm not sure which versions you mean here -- there are some old 0.5.x
releases, but the one that is current and usable is 0.5.6 from GitHub
http://github.com/railfrog/railfrogcms
If you really need to use an older version, we may be able to help, but
expect the learning curve to be steep ;-)
If you use the GitHub version and follow the directions then you'll get
*Rails* 2.0.5 installed as a component.
Ask here or on #railfrog if you get stuck.
-- Thomas