Originally Posted by FlyingToast
Unfortunately at this moment I have no idea how to run mods with Minecraft on a mac. Hopefully there is a way though, I need to just do a bit of searching
Might've found it already but...
Go to Applications Folder > Utilities > Terminal (or Spotlight and search for terminal).
Then, when it loads paste this code into it:
jar xf ~/Library/Application\ Support/minecraft/bin/minecraft.jar
Then simply click enter.
Next, go to Finder and open up your user folder. (Mac HD > Users > Your Name) There should be a mctmp folder in there. In your mod folder, copy and paste the .class files into the mctmp folder.
Finally, go back in terminal and enter this final code:
jar uf ~/Library/Application\ Support/minecraft/bin/minecraft.jar ./
rm -rf mctmp
Your done! -- If it's fly mod then I reccomend looking up MyCraft otherwise it is extra work to install it.