Unfortunately I have no experience with OS X on the Arduino end of things.
However, judging by the migration guide, it should just be a matter of appending /avr/ to the hexbright folder on any platform.
For example, if previously on Windows the file would be placed at:
Then the new location would be:
( confirmed to be working - requires Arduino IDE restart )
One install method for OS X would be to do much the same, with the location being:
If that doesn't work, you would indeed have to go through the .app file. The old location:
Appears to have changed to:
The same copy/paste approach of adding the definition for the HexBright board should then work.