You can create a variable for it but you'll hit the code-before-stage problem. Basically your class constructor can be run at "frame -1" so that everything is set up properly before everything is added into the display list...to work around that you need to wait until the display items are all added before you grab the reference to the textfield.
PHP Code:
public var TF1:TextField;
// constructor
public function MC1(){
addEventListener(Event.ADDED_TO_STAGE, function(e:Event):void{
removeEventListener(Event.ADDED_TO_STAGE, arguments.callee);
TF1 = TextField(getChildByName('TF1'));
});
}