This will show you how to install a texture pack on your Mac. It is easy as 1-2-3 and is one of the best way to do it and also the fastest way.
Step 1: Download your texture pack
Step 2: Make a folder for your texture packs (optional but recommanded)
Step 3: Drag the texture pack folder into your Texture packs folder
Step 4: open the texture pack folder
Step 5: Copy Minecraft and copy it in the texture pack folder
Step 6: Now, if you want to run Minecraft with your texture pack, run the Minecraft that you have put in the texture pack folder.
Step 7: Enjoy!