git clone git://github.com/sickpig/vim.git /path/to/repo
cd /path/to/repo
git submodule init
git submodule update
cd ~
ln -s /path/to/repo/vimrc .vimrc
ln -s /path/to/repo/vim .vim
and now celebrate ;)
if you plan to add new plugins just add new submodule to your local repo, then if you need to update those (custom) submodules just issue:
git submodule foreach git pull origin master