Fire a Magento event from CLI

fireEvent.php

<?php

require 'app/Mage.php';
error_reporting(E_ALL | E_STRICT);
ini_set('html_errors', 1);
Mage::setIsDeveloperMode(true);
ini_set('display_errors', 1);

$orderId = $_GET['order_id'];

Mage::app('');
try {
    $order = Mage::getModel('sales/order')->load($orderId);

    Mage::log($order->getData());
    Mage::dispatchEvent('sales_order_payment_pay', array('order' => $order));

} catch(Exception $e)
{
    echo "exception<br/>$e";
}