I had to look it up but this lives in `.dir_locals.el` in the root of the git repo. Including the comments of what to put in .emacs I think that's everything needed:

    (
     ( nil .
           ((eval git-auto-commit-mode 1))
           )
     )

    ;; and chuck this in your .emacs
    ; (setq-default gac-ask-for-summary-p t)
    ; (setq-default gac-automatically-push-p t)