Codigo js para scroll medio nada mas. http://stackoverflow.com/questions/7154967/jquery-detect-scrolldown

scroll.js

$('body').on('DOMMouseScroll mousewheel', function (e) {
  if(e.originalEvent.detail > 0 || e.originalEvent.wheelDelta < 0) { //alternative options for wheelData: wheelDeltaX & wheelDeltaY
    //scroll down
    console.log('Down');
  } else {
    //scroll up
    console.log('Up');
  }
  //prevent page fom scrolling
  return false;
});