ActionScript 2.0 :: Text Snap Shot, Text Field, Strings?

I need to load textbox.text in to string Obj and find the x y coordinates of some characters by the start and end index of that string. I am already doing this by using textSnapShot class and it is working great, but this class is working only on static textbox it is not working on dynamic textbox. any one knows any way of doing this! here is the snapshot function it returns xy coords:

function GetStringXY(startindex, endindex):Array{
var xy:Array = new Array();
var mc:MovieClip = this;

[code]........