While I don't have a like to point you to, I'd say look at doing it via a web viewer and use one of the many lightbox jquery systems out there. The toughest part will likely be building the HTML in FileMaker.
You could use a script-trigger which does a set-field to the value of a container field... but you would have to have them click... ie no mouse-over.
LOL David Z.... I should learn to reload the page before answering...