function hijackFZDiv(el) {
  var div = $(el.readAttribute('href').gsub(/^#/, ''));
  var src = div.readAttribute('src');
  if (src) {
    var w = parseInt(div.readAttribute('imagewidth'));
    var h = parseInt(div.readAttribute('imageheight'));

    // get viewport dimensions and subtract a little padding 
    var vpDims = document.viewport.getDimensions();
    vpDims = {width: vpDims.width - 100, height: vpDims.height - 150};

    // scale image to viewport dimensions if necessary
    if (w > vpDims.width) {
      h = h * (vpDims.width / w);
      w = vpDims.width;
    } 
    if (h > vpDims.height) {
      w = w * (vpDims.height / h);
      h = vpDims.height;
    }

    // Resize or create image
    var img = div.down('img');
    if (img) {
      img.width = w;
      img.height = h;
    } else {
      img = Element('img', {'src': src, 'width': w, 'height': h});
      div.insertBefore(img, div.firstChild);
    }
  }
}