Event.observe(window, 'load', function() {
  if (!window.XMLHttpRequest) { // IE6, older browsers
    $$('.mmsList table tr', '.buttons .btn').each( function(e) {
        Event.observe(e, 'mouseover', function() { Element.addClassName(e, 'hover'); });
        Event.observe(e, 'mouseout', function()  { Element.removeClassName(e, 'hover'); });
    });
  }
});