I'm attempting to add layered navigation to a CMS page containing a widget that contains a custom product collection (products that are 'new').  Within this widget are fuctions that, given the correct parameters, will filter this collection.  How do I pass this collection to the layered navigation block and have it's attributes show up?

This is how I am calling the layered navigation in the CMS custom layout XML: 

    <reference name="content">
            <!-- Layered Navigation Block -->
            <block type="catalog/layer_view" name="catalog.leftnav" before="-" template="catalog/layer/view.phtml" >
            </block>
    </reference>

This is how i'm calling the product collection onto the CMS page:

    {{widget type="catalog/product_widget_new" display_type="new_products" show_pager="1" products_count="60" template="catalog/product/widget/new/content/new_grid.phtml"}}

This is how i'm generating the product collection:

    protected function _getProductCollection()
    {
        $todayStartOfDayDate = Mage::app()->getLocale()->date()
            ->setTime('00:00:00')
            ->toString(Varien_Date::DATETIME_INTERNAL_FORMAT);
        $todayEndOfDayDate = Mage::app()->getLocale()->date()
            ->setTime('23:59:59')
            ->toString(Varien_Date::DATETIME_INTERNAL_FORMAT);
        /** @var $collection Mage_Catalog_Model_Resource_Product_Collection */
        $collection = Mage::getModel('catalog/product')->getCollection()->addAttributeToSelect('*')->setVisibility(Mage::getSingleton('catalog/product_visibility')->getVisibleInCatalogIds());
        $this->_addProductAttributesAndPrices($collection)
            ->addStoreFilter()
            ->addAttributeToFilter('news_from_date', array('or' => array(
                0 => array('date' => true, 'to' => $todayEndOfDayDate),
                1 => array('is' => new Zend_Db_Expr('null')))
            ), 'left')
            ->addAttributeToFilter('news_to_date', array('or' => array(
                0 => array('date' => true, 'from' => $todayStartOfDayDate),
                1 => array('is' => new Zend_Db_Expr('null')))
            ), 'left')
            ->addAttributeToFilter(
                array(
                    array('attribute' => 'news_from_date', 'is' => new Zend_Db_Expr('not null')),
                    array('attribute' => 'news_to_date', 'is' => new Zend_Db_Expr('not null'))
                )
            )
            ->setPageSize($this->getProductsCount())
            ->setCurPage(1);
        return $collection;
    }