Mesh properties greyed out

So i want to change the occlusion culling properties of base meshes I’ve imported, but the panel for doing so (imported object panel) is greyed out and unusable. I don’t really want to go through all of my scenes, potentially a lot, marking each object individually when I already know what occlusion properties they should have.

Make a prefab: http://unity3d.com/support/documentation/Manual/Prefabs.html