Commands taken from Synchronizing plugins with git submodules and pathogen. Mirrored here for future reference.
git submodule add http://github.com/username/vim-repository.git vimfiles/bundle/repository
git add .
git commit -m "Added repository.vim"
git clone http://github.com/chrisbura/dotfiles.git
cd dotfiles
git submodule update --init
git submodule foreach git pull origin master