Open the .app by right-clicking and selecting 'Show Package Contents'. Go into the Contents/Resources/autorun folder and you'll find the 'Game' folder. Now drag RinTimberPerpective.rpa into this folder.
Now when you chose 'Bonus Content' from the main menu, you will be able to play Rin-Timber's version of Alpha Hole Prison.
We've updated the download instructions with this information.