Can you place images within comments?

I wanted to see if I could make little images much like the ones provided in the Help boxes for the built-in blocks. I've tried a couple of things but could not manage to place one inside. Is this possible and is there any sort of method to do this (either normally or via JS?)

Well, by definition you can do anything in JS! But no, we haven't really built that yet, although it's part of Dylan's internationalizable-help-screen pull request, which should be available sooner or later... It's something we all know we want.