Full code after the jump.

View MXML

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2007/12/30/changing-the-colorpicker-controls-nested-text-field-styles-in-flex-3/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="top"
        backgroundColor="white"
        creationComplete="init();">

    <mx:Style>
        .myCustomSwatchPanelStyleName {
            textFieldStyleName: redBold;
        }

        .redBold {
            color: red;
            fontFamily: Courier;
            fontWeight: bold;
            letterSpacing: 1;
        }
    </mx:Style>

    <mx:ApplicationControlBar dock="true">
        <mx:Form styleName="plain">
            <mx:FormItem label="editable:">
                <mx:CheckBox id="checkBox"
                        selected="false" />
            </mx:FormItem>
        </mx:Form>
    </mx:ApplicationControlBar>

    <mx:Form>
        <mx:FormItem label="default:">
            <mx:ColorPicker editable="{checkBox.selected}" />
        </mx:FormItem>
        <mx:FormItem label="textFieldStyleName:">
            <mx:ColorPicker id="colorPicker"
                    editable="{checkBox.selected}"
                    swatchPanelStyleName="myCustomSwatchPanelStyleName" />
        </mx:FormItem>
    </mx:Form>

</mx:Application>

View source is enabled in the following example.