mustella/tests/components/DateField/swfs/components/myCustomDF.mxml

<mx:DateField xmlns:mx="http://www.adobe.com/2006/mxml"
    yearNavigationEnabled="true" 
    skin="@Embed('../../../../../Assets/Images/up.JPG')" 
    upSkin="{null}" 
    overSkin="{null}" 
    downSkin="{null}" />