From Git, dotfiles & Hardlinks:
symlinking files inside the repository out of it, into your home directory:
~ $ rm ~/.emacs.d
~ $ cd ~
~ $ ln -s dotfiles/.emacs.d .$ brew install emacs --HEAD --with-cocoa --with-modules --with-ctags --with-dbus --with-gnutls --with-rsvg --imagemagick$ brew tap railwaycat/emacsmacport
$ brew install emacs-mac