Parameters code help

I have a movieclip that loads onto my base swf that acts like a menu. Only it’s a set of buttons. I am trying to get the effect of a drop down menu with it. Basically, I need the buttons movieclip to fade out (unload) whenever the users mouse cursor is away from the buttons area. When the mouse hits that area again, the clip should fade back in and the buttons would be clickable.

So I guess I need to set up parameters for this movieclip to deactivate whenever the mouse is far enough away from it… Only I have no idea how to do this…well, I have a clue but no more…

(I am using loadmovieNum command and levels to load the external buttons movieclip into my main movie, if that makes any difference)
Any suggestions?