Cloning this repository:

git clone git://gitorious.org/notepad2-x86-64/notepad2.git notepad2
cd notepad2

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

git remote add notepad2 git://gitorious.org/notepad2-x86-64/notepad2.git
git fetch notepad2
git checkout -b my-local-tracking-branch notepad2/master_or_other_branch