Yes, that location should work fine for PEAR packages, but ensure the PEAR path is correctly configured in your php.ini file under include_path for proper functionality.

To set a custom ruleset in PHPStorm: Go to File > Settings > Editor > Inspections. Find and enable PHP CodeSniffer & PHP MessDetector in the list, then set your ruleset file under the configuration for each tool.

For Magento ECG standards, clone the repository and point the ruleset path in PHPStorm to the ruleset.xml file from the cloned directory.