Figured it out.
class Practice extends MovieClip {
var myObject:Object;
//
public function Practice() {
myObject = new Object();
//
var me:Practice = this;
//
myObject.onMouseDown = function() {
// call doSomething here
me.doSomething();
};
Mouse.addListener(myObject);
}
//
public function doSomething() {
trace("did something");
}
}