Interesting, I didn't think to use the methods hanging off the IList. This would certainly give us a work-around. Although like you, I was hoping to bind this directly to my ViewModel. It would involve a bit of code hanging off the event handlers on the control to keep this list updated in both directions.
Telerik, can you tell us was this an oversight, making this property ReadOnly or done purposely? It would help us determine a course of action.