The near standard cross-browser JavaScript function to add events from Scott Andrew:

function addEvent(obj, evType, fn, useCapture){

  if (obj.addEventListener){
    obj.addEventListener(evType, fn, useCapture);
    return true;
  }
  else if (obj.attachEvent){
    var r = obj.attachEvent("on"+evType, fn);
    return r;
  }
  else {
         obj[’on’+evType] = fn;
  }
}