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.
Thank you so much for sharing, worked like a charm on 10.10.3. Wish I'd found this a day or two ago!
One modification, this patch:
http://answers.ros.org/question/207470/error-compiling-rosbag_storage-on-mac-os-x-yosemite/
... then a fresh catkin build.