In order to be more efficient in pinpointing the best solution for what you wish to accomplish I will need further information. For example, the setup of the RadRotator and the method, through which you set the current item. Also, please, find attached a sample web site with a RadRotator that tries to simulate the behavior you have described. The images are changed through a mouse click and the animation reacts according to the currently selected item. This implementation has nothing special. It utilizes the built-in functionality of the RadRotator itself.
All the best,
the Telerik team