How about baking predefined shadow volume objects? Like dynamically creating an entity which would have the size and form of the shadow volume. Then you could easily assign an action to the moving object with EVENT_ENTITY and could handle the stuff you want to happen if it is in the shady side. Though this won't really work well if you got a dynamic day/night system as the shadow-volume would change continously. Therefore it would be necessary to bake the shadow-volume entities over and over again resulting in the loss of speedgain.
Though otherwise you could have the engine handle everything.

Hope you get the idea X-D