Use this generator

Insert the polynomial coeficients given by the generator instead of t, t2, t3, t4 and t5

t5*(p*p*p*p*p) + t4*(p*p*p*p) + t3*(p*p*p) + t2*(p*p) + t*p

Example shown for easeOutElasticBig

<div data-0="opacity[easeOutElasticBig]:0"></div>
<script>
  $(function() { var s = skrollr.init({ 
    easing: {
      easeOutElasticBig: function(p) {
        return 56*(p*p*p*p*p) - 175*(p*p*p*p) + 200*(p*p*p) - 100*(p*p) + 20*p;
      }
    }
  });});
</script>