This procedure doesn't work for me (CS4, OS X). I get an empty TextField. 

But I found a way to make it work. Instead of this: 

[ Embed ... ] 
private static var EMBEDDED_FONT:String; 

I do this: [ Embed... ] 
private static var EMBEDDED_FONT:Class; 

(Note: Class instead of string) 

Then, assuming that statement is in a class called Assets, when I want to use that font in another class, I do this: 

import flash.text.TextField; 
import flash.text.TextFormat; 
import flash.text.Font; //<-- note this import

...

var t : TextField = new TextField();
var f : TextFormat = new TextFormat();
var font : Font = new Assets.EMBEDDED_FONT();

f.font = font.fontName; //<-- note this difference

t.embedFonts = true;
t.text = "test";
t.setTextFormat( f );