This should apply to RHEL5 as well, but I haven’t verified yet. The easiest solution I’ve found is to simply install Ruby and it’s dependencies and then install RubyGems from source. I’ve written a small script which installs Ruby and it’s dependencies. It then grabs the RubyGems source tarball and installs Gems from source. As I wrote this to get a working Chef install, it also adds an opscode gems source.