Usage:
 	Tweener.addTween(myMc, { _x:500, _y:30, base:Mot.base0 } );
 	Tweener.addTween(myMc, { base:Mot.fadeOut } );
 	Tweener.addTween(myMc, { base:Mot.fadeTo(50), onComplete:myCallBackFn} );