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.
Now installing on my Yosemite machine. A few other updates including changing the paths for Python 2.7.9, using skip-keys and as-root in the rosdep invocation, and adding sphinx to the upfront pip install (for the sake of a homebrew dependency).