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.
it fails with Xcode 6.3 / Xcode CLT 6.3. I had to downgrade to 6.2 (fails compilation of roscpp and several other packages in the catkin build last step)