makeLightboxLinks = function() {
  var images = document.getElementById('content').getElementsByTagName('img');
  for (i = 0; i < images.length; i++) {
    var s = images[i].getAttribute('src');
    if (s.search('thumb') >= 0) {
      var a = document.createElement('a');
      a.setAttribute('rel', 'lightbox');
      a.setAttribute('href', s.substring(s.search('img=') + 4));
      var img = images[i].parentNode.replaceChild(a, images[i]);
      a.appendChild(img);
    }
  }
  initLightbox();
}

Event.observe(window, 'load', makeLightboxLinks, false);