alter script to load externally

i have this script which animates the text string in one character at a time
(dynamic textfield instance name = display_txt).


stop();
var mystr = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit";
function doVidiprinterEffect(textfield,strtext)
{
if(strtext == undefined)
{
strtext = textfield.htmlText;
textfield.htmlText = "";
}
var string_index = 0;
var max_index = strtext.length;
this.onEnterFrame = function()
{
textfield.text += strtext.charAt(string_index);
string_index++;
if(string_index == max_index)
{
this.onEnterFrame = undefined;
}
}
}
doVidiprinterEffect(this.display_txt);



can anyone tell me how edit it to take a string of text from an external txt
file instead. i cant figure it out so that it loads and also uses the printer
effect.

thanks