I concur with Katopz. In most of my Away3D Lite projects I define a custom layer sprite (Plane.layer property) and use regular Flash MouseEvents or Signals. This seems to work and shows the hand cursor. The only issue I had was with double sided planes, when the back side is showing the mouse cursor wouldn't show. Also if you are looking for performance use MovieMaterial only if you have no other choice. It consumes a lot of CPU by re-drawing at every frame/render.
If you have buttons inside your MovieMaterial's sprite and need those to be interactive, I don't think Away3D Lite supports it. At least it didn't last year! I ended up having to use modeled objects for floor plans in my project. In the end, I think by doing so, performance and looks were improved. This is the project I am referring to: http://sashawaltz.neuesmuseum.com/ It's not quite finish, but uses Planes with mouse events on the layer sprites (arrows and dancers). The floor plan on the left was originally in a sprite but ended up being a 3D model exported via Prefab to an AS3 Class.
