Make sure you have pear installed:
sudo pear upgrade-all - If this fails then install pear, if it works then congrats on updating all your pear extensions
sudo pear install PHP_CodeSniffer
OSX Only - sudo cp /private/etc/php.ini.default /private/etc/php.ini
Add include_path = ".:/php/includes:/usr/lib/php/pear/" to php.ini, not to change your includes directory to where pear is installed!
Now for Drupals cs patterns:
Download Coder module - https://drupal.org/project/coder
Untar to a directory e.g. ~/Projects/coder
PHPStorm Config:
PHPStorm > Settings > PHP > Code Sniffer
To find the phpcs path type which phpcs
Then use that path in PHPStorm
Click validate to test whether it works or not.
You should also increase the tool process timeout as it takes a while to test core files.
While still in settings select Inspections, drill down to phpcs in PHP and enable the point the coding standard to wherever you downloaded coder to.