[AS3] events

I whipped something up really quick and wanted to know if someone could help me. Right now I built a context menu class that just pulls its information from a XML file. That works fine and I also built a MainNav class that I have linked to a MC on my stage.

Everything works fine my question is since I have my MainNav class linked to the MC on the stage how can I access it from the Main class? Because I would eventually like to have it setup so that when you view the swf the preloader does it thing then the nav will tween in like it currently does. As of right now it tweens from the start but I would like to add a listener or something to that extent so that once the xml/preloader is done loading then to this.

FYI: In your class path you will have to have it like …/classes to work with my folder structure.

Thanks