To use it just instantiate new ViewNavigator passing your application sprite as constructor parameter.
Next you have following functions available:

public function pushView(view:Sprite):void;

public function popView():void;

public function popToFirstView():void;

public function popAll():void;

public function replaceView(view:Sprite):void;

public function get poppedViewReturnedObject():Object;

public function get length():int;