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Do you know how to install modloader or forge?

 

First, download liteloader and macromod from here.

1. Make sure you are using a clean, un-modded .minecraft.
2. Go into Finder and type "shift + command + G", this will open up the "Go to Folder" search.
3. Type in "~/library"
4. Click on the "Application Support" folder and find your "minecraft" folder.
5. Go into your "bin" folder and find the Minecraft.jar.
6. Open Minecraft.jar with The Unarchiver.
7. Rename the "minecraft" folder that is placed on your desktop to "minecraft.jar"
8. Drag that folder into your "bin" folder and replace the other minecraft.jar
9. Open the liteloader zip file that you downloaded.
10. Copy and paste everything into your "minecraft.jar"
11. Delete the "META-INF" folder.
12. go back to the .minecraft folder
13. open the mods folder, if it doesn't exist, create it.
14. copy/paste the macro mod litemod file into the mods folder
15. run minecraft

(taken from da_tirtow's tutorial for installing CJB on mac, and edited for liteloader/macro mod)

 

The Unarchiver is a program on mac os x to open zipfiles. Use it to open minecraft.jar