Cloning this repository:

git clone git://gitorious.org/mongomapper-s-openid-authentication/mmoid.git mmoid
cd mmoid

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

git remote add mmoid git://gitorious.org/mongomapper-s-openid-authentication/mmoid.git
git fetch mmoid
git checkout -b my-local-tracking-branch mmoid/master_or_other_branch