Cloning this repository:

git clone git://gitorious.org/gentoo-ebuilds-maintenance/ruby-ebuilds.git ruby-ebuilds
cd ruby-ebuilds

Add this repository as a remote to an existing local repository:

git remote add ruby-ebuilds git://gitorious.org/gentoo-ebuilds-maintenance/ruby-ebuilds.git
git fetch ruby-ebuilds
git checkout -b my-local-tracking-branch ruby-ebuilds/master_or_other_branch