- which git --> /usr/local/git/bin/git, so /usr/local/git is {GIT_HOME}
- cp {GIT_HOME}/contrib/completion/git-completion.bash ~/.git-completion.sh
- vi ~/.profile (or .bashrc if on Linux)
- insert into end of .profile:
source ~/.git-completion.sh
PS1='[\u@\h \W$(__git_ps1 " (%s)")]\$ '
Open a new terminal window and enjoy.