Another basic little example showing how to format the text in a DateField control using the DateFormatter and the DateField control’s labelFunction property. This entry also shows the pretty basic trick of creating a separate ActionScript class file that holds the day names as constants so you don’t constantly have to think whether Monday is day 0 or day 1 (hint: it is day 1).
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="vertical" verticalAlign="middle" backgroundColor="white">

    <mx:Script>
        <![CDATA[
            private function doLabel(item:Date):String {
                return dateFormatter.format(item);
            }
        ]]>
    </mx:Script>

    <mx:DateFormatter id="dateFormatter" formatString="MMM D, YYYY"/>

    <mx:DateField todayColor="red" labelFunction="doLabel" firstDayOfWeek="{Days.MONDAY}" />

</mx:Application>

Days.as
// ActionScript file
package {
    public class Days {
        public static const SUNDAY:uint = 0;
        public static const MONDAY:uint = 1;
        public static const TUESDAY:uint = 2;
        public static const WEDNESDAY:uint = 3;
        public static const THURSDAY:uint = 4;
        public static const FRIDAY:uint = 5;
        public static const SATURDAY:uint = 6;
    }
}