Magento: Update layout or add js with controller

public function myAction()
{

    /* ... Some code ...*/

    $update = $this->getLayout()->getUpdate();

    /* ... Some code ...*/

    $this->addActionLayoutHandles();

    /* ... Some code ...*/

    $this->loadLayoutUpdates();

    /* ... Some code ...*/

    $update->addUpdate('
        <reference name="head">
            <action method="addJs"><script>varien/product.js</script></action>
            <action method="addItem"><type>js_css</type><name>calendar/calendar-win2k-1.css</name><params /><!--<if/><condition>can_load_calendar_js</condition>--></action>
            <action method="addItem"><type>js</type><name>calendar/calendar.js</name><!--<params/><if /><condition>can_load_calendar_js</condition>--></action>
            <action method="addItem"><type>js</type><name>calendar/calendar-setup.js</name><!--<params/><if /><condition>can_load_calendar_js</condition>--></action>
            <action method="addItem"><type>skin_js</type><name>js/bundle.js</name></action>
        </reference>
    ');

    /* ... Some code ...*/

    $this->generateLayoutXml()->generateLayoutBlocks();

    /* ... Some code ...*/

    $this->renderLayout();

}