These instructions have been supplanted by an automated, scripted installer, which lives here:
https://github.com/mikepurvis/ros-install-osx
Please try it out, and file bugs as required. Feel free to browse past versions of this gist as a historical curiosity, but I won't be monitoring or supporting it any more.
@davetcoleman, it's odd to me that pydot would require a manual installation— it's clearly in the rosdep index. Is it rqt_graph, or is there some other package you're thinking should have the dependency?