function addCustumOnRelease(target:MovieClip) {
    for (var prop in target) {
        if (target[prop] instanceof MovieClip) {
            if (target[prop].onRelease != undefined) {
                target[prop].originalOnRelease = target[prop].onRelease;
    
                target[prop].onRelease = function() {
                    this.originalOnRelease();
                    trace('custum');
                }
            }
            else {
                arguments.callee(target[prop]);
            }
        }
    }
}

addCustumOnRelease(_root);