You can use a jQuery plug-in (for instance here is an example that I believe would be very useful in your case http://lokeshdhakar.com/projects/lightbox2/);
Implement your own lightbox using css and javascript as described here.
Kind regards,
Kate
the Telerik team
If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to their blog feed now.