Hide Comments from Non-Members?

Ok, I've been searching for days now for the answer to this, at least one for the novice. In WP forums, some say being able to hide comments on posts from public view is a "theme level" thing. Others say there are plug-ins for this. I have yet to find one that offers a simple installation or instructions for modifying a PHP file that make any sense to a beginner.

Am I looking for something that just doesn't exist?!
I'm using a Hidepost plugin to restrict POSTS to registered members, but the comments under those posts are STILL totally PUBLIC (which I don't want!)

Any ideas? Anyone? Anywhere? Ack!