slowing down javascript autoscroll function

humble newbie here. i found this javascript autoscroll function and got it to work by pasting it in the header file of a wordpress site. however, i'd like to slow down the scroll so that it does not immediately snap to the bottom of the page. i am brand new to javascript and could not get any other autoscroll functions to work on my site so am hoping i can just adjust this function by adding a speed variable. many thanks!

<script type="text/javascript"><!--

   function AutoScrollOnload() {


var InFromLeft = 172;
var DownFromTop = 964;


window.scrollTo(InFromLeft,DownFromTop);
}
function AddOnloadEvent(f) {
if(typeof window.onload != 'function') { window.onload = f; }
else {
   var cache = window.onload;
   window.onload = function() {
     if(cache) { cache(); }
    f();
     };
   }
 }
AddOnloadEvent(AutoScrollOnload);
 //--></script>