如何仅引用TextArea的htmlText块的一部分？

I have a number of very poor-quality pdf documents that look like 80's photocopies, which I'm rebuilding in Flash (Flex Builder 3 MXML application), representing paragraphs of text in TextAreas so that selected portions can be bold or italic, or whatever I need. I need a way to apply toolTips or event listeners to individual words within the block of text to link those words to a glossary. I'm perfectly happy to create a definition panel that is populated and made visible with a mouseOver, but don't know how to do it to just a portion of the text.I have a number of very poor-quality pdf docume