writeon Text Effects????Help please!

[neilnewflashuser]

I work in film and am trying to create some interactive flash text pages. Maybe someone knows how. An example is Carrie on "Sex & the City" she's not typing, it's a flash page. Everytime she touches any letter on the keyboard a letter is shown. How do I do this so it doesn't play the whole paragraph just one letter each time? This is what I've figured out so far. THANKS TO WHOEVER CAN HELP ME!

var str:String="In a clear effort to quickly seize the higher.";
var sInt=setInterval(writeIt,15)
var count:Number=0;
function writeIt(){
theText.text=str.substring(0,count);
count++;
if(count>str.length){
clearInterval(sInt);
}
}