mediabox.scanpage = function() {
  var links = $$("a").filter(function(el) {
    return el.rel && el.rel.test(/^lightbox/i);
  });
  $$(links).mediabox({/* put custom options here */}, null, function(el) {
    var rel0 = this.rel.replace(/[[]|]/gi," ");
    var relsize = rel0.split(" ");
    return (this == el) || ((this.rel.length > 8) && el.rel.match(relsize[1]));
  });
};
window.addevent("domready", mediabox.scanpage);