via a RadAjaxManager or a full postback from a (hidden) button
in the callback function (which can actually also be an AJAX request if the button is inside an update panel).
All the best,
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