I know this is an old thread but i found it and it helped me. As Palmsey has mentioned in the one of the comments, the scrollTo Demo shows an example of using easing, but doesn't actually mention that it has borrowed a small snippet of code from the easing plugin found at http://gsgd.co.uk/sandbox/jquery/easing/. The demo on scrollTo includes this code in the init.js file
//borrowed from jQuery easing plugin
//http://gsgd.co.uk/sandbox/jquery.easing.php
$.easing.elasout = function(x, t, b, c, d) {
var s=1.70158;var p=0;var a=c;
if (t==0) return b; if ((t/=d)==1) return b+c; if (!p) p=d*.3;
if (a < Math.abs(c)) { a=c; var s=p/4; }
else var s = p/(2*Math.PI) * Math.asin (c/a);
return a*Math.pow(2,-10*t) * Math.sin( (t*d-s)*(2*Math.PI)/p ) + c + b;
};
However if you include the entire easing plugin mentioned above you can use any of the functions mentioned at http://easings.net/