Magento: add proceed to checkout button to message

<?php
$URL="http://" . $_SERVER['SERVER_NAME'] . "/sites/default/files/magento/cart/CartController.php.diff";
echo "

";
$c = curl_init();
curl_setopt($c, CURLOPT_URL, $URL);
echo htmlspecialchars(curl_exec($c));
curl_close($c);
echo "

";
?>

Optional: fix CSS
add to ./skin/frontend/default/default/css/styles.css
.proceed-to-checkout {
padding-top:8px;
}