Is it possible to have an external script run index.php that bootstraps Drupal?
To answer your question - Yes, it is possible to have an external script to bootstrap Drupal.

If Drupal is installed in the folder [root], and the index.php file that you want to get working is in [root/myscript], you'd first get the working directory and then call bootstrap.inc and bootstrap Drupal.

&lt;?php
define('DRUPAL_ROOT', getcwd());
require_once DRUPAL_ROOT . '/../includes/bootstrap.inc';
drupal_bootstrap(DRUPAL_BOOTSTRAP_FULL);
// do your thing
?&gt;