How can I "highlight" different words in text for a "read-a-long"

Was talking with Mike Lee about Lubutto project and showing him Event Theatre and he had the great idea of using it to have folks "record books/stories" kids create.

We would like something to highlight the words as they are read (not auto-magically, the reader could hit a key to highligh to the next word.

But how can I "highlight" (change color/make bold/change backgroung color) for the "next word"?  

We could break the reading into multiple text objects but that would be time consuming and annoying.  

Better to have the computer to what its good at and do it for us.

Any suggestions on how this could be done?

Thanks,

Stephen