Cloning this repository:

git clone git://gitorious.org/freebroid/external_clearsilver.git external_clearsilver
cd external_clearsilver

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

git remote add external_clearsilver git://gitorious.org/freebroid/external_clearsilver.git
git fetch external_clearsilver
git checkout -b my-local-tracking-branch external_clearsilver/master_or_other_branch