Programatic TextField sizing

Ok, so this is all in Actionscript 3.0 in Flash CS3.

I have a TextField I created and added to the stage and I want an MC to change its width to the width of the TextField whenever a new word is programmatically put into the TextField’s text property.

I handle the change, obviously, using an Event.CHANGE listener on the TextField.

The problem is, how do I get the TextField to size itself (width and height) to just fit the text that was programatically inserted? Basically, I want te field to size programmatically the way it does when you put Text on the stage and type a word into it.