Detect when user rolls over certain text in html field?

I’d like to do a term/hint rollover kind of functionality. I have text from XML displaying in an HTML-formatted field, but I’m not sure how to flag a particular word for this. When creating a hyperlink in flash HTML fields, you can of course detect a lick of that link, but can you do anything about when a user rolls over it?

If that’s not possible, what work-arounds might there be to simulate this effect?

I wonder about drawing an invisible clip over the word to which I can add a rollover listener. Doing this would require I know the coords that define a box around the word in the text field - is that possible?