Passing class instance to button code created by that class...

[everfornever]

Not sure I understand 100% but what I think your trying to do is this.

    public function makeButton (mc:MovieClip, string:String) {
        
        var myButton:MovieClip = _root.attachMovie(string, string, _root.getNextHighestDepth())
                                                                                              
        myButton.mc = mc
        
        myButton.onRelease = function (){
            
            trace (this.mc + " created me")
            trace ("I am " + this)
            
        }
        
    }