_root.createTextField("my_txt", 0, 50, 50, 450, 100);
my_txt.text = "Smooth alpha capable dynamic text";
my_txt._quality("BEST")
my_txt.multiline = true;
my_txt.selectable = false; // as your wish...
my_txt.wordWrap = true;
my_txt.embedFonts=true;
// We need a TextFormat object to set format to our textfield
my_fmt = new TextFormat();
//Now we choose the font, using the identifier name of the font symbol
my_fmt.font = "myFont";
my_fmt.size = 28;
my_fmt.color = "0x999999";
//now we apply the format...
my_txt.setTextFormat(my_fmt);
my_txt._alpha = "100"; // whatever you want...