To install clone the repo in your home directory:
$ cd ~/
$ git clone [repo_url] vim
Next you will need to update the plugins which are git submodules:
$ cd vim
$ git submodule init
$ git submodule update
Also you need to create a directory for vim to save backups of files you work on:
$ mkdir sessions
Finally, set up symlinks so vim can pick up the config:
$ cd ~/
$ ln -s ~/vim ~/.vim
$ ln -s ~/vim/vimrc .vimrc
Now when you open vim you should be good to go.
You may want to use tags to aid with completion. If you're on linux you'll want to install exuberent ctags:
$ sudo apt-get install exuberant-ctags
If you're on a mac you will need to install ctags with macports as the version that ships with mac is not compatible:
$ sudo port install ctags
This will install in /opt/local/bin/ctags
Once installed you can use the following to create a php tags file relative to the directory in which you run the command.
$ /opt/local/bin/ctags -f ./tags -h ".php" -R --exclude="\.svn" --totals=yes --tag-relative=yes --PHP-kinds=+cf --regex-PHP="/abstract class ([^ ]*)/\1/c/" --regex-PHP="/interface ([^ ]*)/\1/c/" --regex-PHP="/(public |static |abstract |protected |private )+function ([^ (]*)/\2/f/"
Which will create a file called tags in the current directory. You can get vim to use this tags file with:
:set tags=/path/to/tags