Irrlicht Engine

Since each device only has one scene manager, what is the easiest way to switch between a menu to gameplay? I know i did this in c++ a long time ago with like 0.6 version of the engine, but i don't have the code handy, and i'm using c# now anyway.

Ok, refining my question. Why is there not createNewSceneManager() in .net version? OR why is the constructor ISceneManager.ISceneManager(irr.scene.ISceneManager* manager) which requires a pointer to a another ISceneManager and how do I get such a pointer in C#?