It's in the OP, download the PC version unzip it take the game folder and merge it with the older one in the autorun folder in your Mac version.
The path is: Right click on you game icon/Show package Contents/Contents/Resources/Autorun.
Drag and drop the game folder onto the autorun folder while holding the alt key on your keyboard, click merge in the pop up menu that will appear, and you are good to go.
For the future repeat these steps if you need to update and the Mac version is not available, just take a look a the script number version before ( it's inside the game folder), and verify that is the same or else this operation will not work.