On OSX, you might have a .zshrc file looking like so:
source $HOME/Sites/dotfiles/zsh/config.sh source $HOME/Sites/dotfiles/aliases.sh
Note that aliases should follow config so that local shortcuts override any defined by the oh-my-zsh plugins.
You should also symlink the included custom theme so that oh-my-zsh can find it:
ln -s $HOME/Sites/dotfiles/zsh/pugetive.zsh-theme $HOME/.oh-my-zsh/themes/.