ActionScript 2.0 :: Easing Typewriter

Hi,

I'm trying to create a not that ordinary typewriter. The thing is, that I wan't it to ease. So I just thought that I could use: speed^0.5, but it really doesn't seem to affect the speed?

The idea is, that the first part of the text is written into the textField very fast, and then it types slower and slower...

This code works, but there's no easing, don't now if there's an easy way to add that:
[AS]TextField.prototype.typewriter = function(stringy, func) {
var myText = this;
var i = 0;
var intv = setInterval(function () {
myText.text = stringy.substring(0, i);
i += 2;
if (i>stringy.length) {
clearInterval(intv);
}
updateAfterEvent();
}, func);
};
var mystring = "here goes the text";
var speed = 10;
txt.typewriter(mystring, speed);
[/AS]Thanks, Morten