well otcbb.com has that regsho reporting tool you saw, but it only reports legal booked shorts, and is easily manipulated by covering right before release date then reentering a new short position right after.
you may want to look at buyins.net or shortsqueeze.com but i am sure they are all fairly complicit in their data gathering standards.
Register for free to join our community of investors and share your ideas. You will also get access to streaming quotes, interactive charts, trades, portfolio, live options flow and more tools.