Не запускал, но примерно так:

Код AS3:
package {
import flash.display.*;
import flash.text.*;
import flash.events.*;
public class TextAnimation extends Sprite {
private var t:TextField;
private var textFormat:TextFormat;
private var tText:getXML;
public function TextAnimation() {
t=new TextField();
tText = new getXML();
tText.addEventListener('XMLReady',onXMLREady);
t.text="Привет всем посетителям нашего сайта!";
t.autoSize=TextFieldAutoSize.LEFT;
t.x=500;
textFormat = new TextFormat();
textFormat.bold=true;
textFormat.color=0xFF0000;
textFormat.font="Arial";
textFormat.size=14;
t.setTextFormat(textFormat);
addChild(t);
var square:Sprite = new Sprite();
square.graphics.beginFill(0xFF0000);
square.graphics.drawRect(4, 2, 525, 20);
addChild(square);
t.mask=square;
addEventListener(Event.ENTER_FRAME, moveTextRight);
}
private function onXMLREady(e:Event):void
{
t.text = tText.t_str;
}
public function moveTextRight(e:Event):void {
t.x-=1;
if (t.x+t.textWidth<0) {
t.x=t.textWidth+500;
}
}
}
}
и

Код AS3:
package {
import flash.events.Event;
import flash.events.EventDispatcher;
import flash.net.URLLoader;
import flash.net.URLRequest;
public class getXML extends EventDispatcher
{
private var xmlLoader:URLLoader=new URLLoader(new URLRequest("intelcity.xml"));
private var xmlData:XML;
private var xmlList:XMLList;
public var t_str:String;
public function getXML()
{
xmlLoader.addEventListener(Event.COMPLETE, newXML);
}
private function newXML(e:Event):void
{
xmlData=XML(e.target.data);
xmlList=xmlData.children();
t_str=xmlList[0];
var ev:Event = new Event('XMLReady');
dispatchEvent(ev);
}
}
}