basic bash script to install itemsets from http://lolmath.net/itemsetcreator.html for OSX/Mac League of Legends. This script will install the latest item sets into your league of legends for you, have also included manually install instructions if you don’t want to use the script.
(make sure League of Legends is not open)
Open up terminal and copy & paste the following, and click Y to install.
bash <(curl -Ls https://raw.githubusercontent.com/lukesUbuntu/itemsetinstaller/master/itemsetinstaller.sh)
Download file http://lolmath.net/itemsets/Update.tar.bz2 and untar it will uncompress a Champions folder copy this folder
Go to your Applications folder and find the League of Legends application and right click and select Show Package Contents
It will show the contents of the folder, now navigate to the Config folder which is located in Contents\LoL\Config then paste the Champions folder
You will be prompted that there is already files in there, just click replace
Now your good to go!!!, load up League of Legends and you should see all the new item sets in game.