Drag it into the Resources, and check "Include in document
In the document inspector, uncheck “Protect from external styles”
Create a text block and paste into the internal html your marked up styled text
If you need to modify any styles, do so in the external style sheet; Hype will alert you that the styles have been modified and ask if you want to update the styles; click “update”
I was just contemplating whether or not styles is something Hype user base would benefit Talking Character and Paragraph Styles. If you ask me I sure as heck would. Dreameaver, Photoshop, and almost every other page layout program has this feature.