(Re)move ~/.vim and ~/.vimrc if you have them already, and run:
git clone git@github.com:pivotal/vim-config.git ~/.vim
cd ~/.vim
git submodule update --init
ln -s ~/.vim/vimrc ~/.vimrc
As long as your checkout is kept clean, you can easily update, rebase your local changes and update submodules with:
cd ~/.vim && git pull --rebase ; git submodule update ; cd -