Customising the Thumbnails scroller tutorial

Hi what an excellent tutorial,

I have been playing and fiddling around with this tutorial and have changed the use of it from a photo viewer into a navigation system for my flash site. I have been searching through the forum to help me with my problem but can not find an answer, what I am trying to accomplish is on the image scroller once a image is selected I would like it to highlight that image, so the users can see what image is selected on the scroller.
If anybody has done this before with this tutorial I would be grateful for the link to the thread/post or if anybody has a idea of how to do this could you help us out please,