Hovering Images (based on hovering captions tutorial)

Hello all,
I was wondering if there may be a tutorial out there that expands upon the hovering captions tutorial, except with images.

What I’m looking to do is roll over a button, and in it’s rollover state display an image/movieclip wrapped in a border, similar to how the hovering captions is set up–where the border/container movieclip would stretch based on the size of the image contained within. The caption script has the border/background size based on text.length, so I’m assuming that there should be an easy way to implement this idea with images?

I am inspired by the javascript (showtrail) used on ywft.org, and am looking for a similar effect in flash.

Any help is appreciated!

Cheers,
DC