if (document.getElementsByTagName) {
  var inputElements = document.getElementsByTagName("input");
  for (i=0; inputElements[i]; i++) {
    if (inputElements[i].className && (inputElements[i].className.indexOf("disableAutoComplete") != -1)) {
      inputElements[i].setAttribute("autocomplete","off");
    }//if current input element has the disableAutoComplete class set.
  }//loop thru input elements
}//basic DOM-happiness-check