how do you properly root galaxy s3 i9300 on mac? I am trying to root my Galaxy S3 i9300 on a Apple Mac.

I followed the instructions here

But instead of my phone starting up ClockWorkMod recovery, my phone keeps booting up on android recovery.

Any tips on how to go from here?
Try flashing again, while you do tick off the auto reboot. Then take the battery out when it’s done flashing.  Then enter ClockworkMod Recovery right away. 

PS: Just try if you are ready to experiment. I don't give any guarantee.