Board Thread:General Discussion/@comment-27023597-20151019171613/@comment-1251315-20151019191639

You can request Wikia to enable the Javascript review process (which will unlock the common.js page) by sending a request to Special:Contact/general. Be aware that you'll need to explain why you want it so they can determine if it will be safely used and not abused by the sysops of the wiki.

I recently requested this to be enabled on a few wiki's and they did so. :)