Step 1: Download the mod you want. Step 2: Go to Finder/Library/Application Support/minecraft/bin Step 3: Open up the mod file. Step 4: Right click te minecraft.jar and open it with Springy or folder Step 5: Drag the .class files onto Springy or into te folder. Step 6: Delete META-INF file. Step 7: Highlight all the files in the folder. Step 8: Right click and press compress. Step 9: Find the .zip in the minecraft folder. Step 10: Move it to the bin. Step 11: Name the minecraft.jar you have to minecraft1.jar and name the .zip file to minecraft.jar Step 12: Open minecraft and use your mod.