Cloning this repository:

git clone git://gitorious.org/~drizztbsd/android-n900/drizztbsd-nitdroid-kernel.git drizztbsd-nitdroid-kernel
cd drizztbsd-nitdroid-kernel

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

git remote add drizztbsd-nitdroid-kernel git://gitorious.org/~drizztbsd/android-n900/drizztbsd-nitdroid-kernel.git
git fetch drizztbsd-nitdroid-kernel
git checkout -b my-local-tracking-branch drizztbsd-nitdroid-kernel/master_or_other_branch