Actionscript 3.0 to 2.0

Hi all, I am currently finishing up my ICT coursework, however I can't seem to get past this one issue. The issue occurs with the code I followed of a YouTube video, whereby the individual was using (ActionScript 3.0), however I need it in ActionScript 2.0. The objective is to make a photo gallery, where any image clicked, goes to the back of the pile. For example:

The YouTube Video encase anyone wishes to view it: Ultra Simple Flash Click-Through Photo Gallery with AS3! - YouTube

This is the ActionScript the individual Provided me with, any help with converting it to ActionScript 2.0 would be much appreciated:

master_mc.addEventListener(MouseEvent.MOUSE_DOWN, clickedF);
master_mc.buttonMode = true;

function clickedF(event:MouseEvent):void{
      master_mc.setChildIndex(event.target as MovieClip, numChildren-1);
}

Thanks