Element.addMethods({
  injectBefore: function(element, content) {
    new Insertion.Before(element, content);
    return $(element.previousSibling);
  },

  injectTop: function(element, content) {
    new Insertion.Top(element, content);
    return $(element.firstChild);
  },

  injectBottom: function(element, content) {
    new Insertion.Bottom(element, content);
    return $(element.lastChild);
  },

  injectAfter: function(element, content) {
    new Insertion.After(element, content);
    return $(element.nextSibling);
  }
});