Решение:
//Вывод количества отложенных товаров
if (Core::moduleIsActive('shop'))
{
$oShop = Core_Entity::factory('Shop', 1);
$Shop_Cart_Controller = Shop_Cart_Controller::instance();
$aShop_Cart = $Shop_Cart_Controller->getAll($oShop);
$iPostpone = 0;
foreach ($aShop_Cart as $oShop_Cart)
{
if ($oShop_Cart->Shop_Item->id && $oShop_Cart->postpone == 1)
{
$iPostpone += $oShop_Cart->quantity;
}
}
echo $iPostpone;
}