Yeah, 15 minutes is OK. You can set WGET or curl as a script to call yoursite.com/index.php/module/retrieve, where this will run this code:
class Module extends CodonModule {
public function retreive() {
// your XML parsing code in here,
$cws = new CodonWebService();
$xml = simplexml_load_string($cws->get ('URL to your XML'));
// continue
}
}
And you can do all your parsing, etc there as if it's a regular ACARS module