I am by no means an expert since I'm a mac noob and can't exactly remember how I did it so the most important note below is Step 1.
- Go to your Applications in Finder, make a copy of existing Leap of Faith as a backup (I just copyied mine to desktop). If all the below steps don't work you can then just copy this back to Applications in place of the messed up version!
- In applications, right click the app and 'Show Package Contents'
- In a new finder window, go to the unzipped patch file and right click and 'Show Package Contents'
- Double click through to \Contents\Resources\Autorun
- Copy everything over to the equivalent location of the game in the Applications folder
- Hopefully it works! As I say, can't remember how I did it exactly but it's something like the above - if it doesn't work then try copying over the contents within 'game' and 'renpy' separately.
- If it goes wrong, just delete the app and copy the backup from your desktop back into applications and experiment some more.
There may well be a simpler way to do it but as previously mentioned, I'm a mac noob!