Updated for OCTGN 3.2.75.0
tested on macOS El Capitan 10.11.6
Original version here https://gist.github.com/samuellinde
Disclosure: These instructions are provided as-is. I don't take any responsibility for things that might go wrong (though the worst thing that could happen should be that OCTGN just won't run). I don't have time to support you if things don't work, unfortunately. But hopefully you'll get OCTGN running without needing to use a virtual machine like Parallels or VirtualBox.
Statements like these are commands to be run in the terminal. You should be fine just copying and pasting, just don't miss any characters.