Thank you for the question.
In order to enable scrolling on mouse wheel 'click', you should inherit RadPanel control and override its OnMouseWheel method. The scrolling logic should be implemented there. Simply, you need to call LineUp() and LineDown() methods of RadScrollViewer and this will scroll the items for you. I am attaching a sample project where this approach is demonstrated.
If you have additional questions, feel free to contact me.
the Telerik team