_root.createTextField("test_txt", this.getNextHighestDepth(), 0, 0, 400, 100);
var myCSS:TextField.StyleSheet = new TextField.StyleSheet();
myCSS.setStyle(".display", {letterSpacing:'15px'});
test_txt.styleSheet = myCSS;
test_txt.text = '<span class="display">red_________red</span>';

I needed a way to dynamically space out letters. Here's an example using style sheets in Flash.

AS2: Dynamically space out letters

ActionScript