Displaying Images in Hovertips

I'm hoping someone could explain to me the process for displaying images in hovertips, please. I'm assuming it can in fact be done, because there's at least one issue ticket that's related.

I have the image displaying correctly on the glossary page. I've tried two methods for this:
1. by inserting a standard tag inline (and changed input format to either filtered HTML or full HTML (and enabled Glossary filter for both); and
2. By using the Taxonomy Image module.

But in neither case does the image display in the actual hovertip. I've also looked at the Hovertip and Clicktip module, but it doesn't appear that that will solve the problem.

Using method 1, the behavior I get is that the code is converted to playing text in full, along the lines of "<" being converted to "<" and the full link written inline in plain text, etc.

Using method 2, there's no indication in the hovertip at all that there's an image or extra code.

Between tests I've cleared the Taxonomy cache as well as browser cache, and have tried in both Firefox 3 and Safari 4.

This is in Drupal 6.11.

Many thanks in advance to anyone who can help.