Hi M Mayo,
Unfortunately such functionality cannot be achieved with RadChart for ASP.NET AJAX.
At the moment we are working on a WPF charting and gauges suite that should be available as a community technology preview later this month. Our current estimates are that we will be able to release the control by the end of the year and once we are ready with it, we will port the relevant codebase to Silverlight so you will be able to utilize it in ASP.NET project as well.
the Telerik team