Step one:
cat <<EOF >>~/.gitconfig
[alias]
review = !sh \`git rev-parse --show-toplevel\`/tools/rfc.sh
EOF
Step two (with your Launchpad username):
git remote add gerrit ssh://$username@review.openstack.org:29418/openstack/horizon
If it worked, you can now run:
git review
That should give you a success message on a clean (unchanged branch), or submit changes for review if your branch is ahead of master.