I'm not sure if anyone else will run in to any roadblocks when initially trying to load/run the game on MAC OS X, but i figured i would post a quick little guide for the three steps required for setting Java permissions.
Make sure you have the latest version on Java installed, Here.
From system preferences open up your java control panel, APPLE ICON>SYSTEM PREFERENCES>JAVA. Access the SECURITY tab, and add the client URL to the permissions list. Once added a prompt will inform you that adding HTTP url's is unsafe, add the url anyway.
You should now be able to load and run the P5 client with your safari browser. Let me know if you have any trouble or questions. Also MODS, feel free to delete/move/sticky this as you see fit.