Actually, they are returned as part of the "attrlist" attribute of the object which gets returned from fetch_event.
This code might help people:
$event=mcal_fetch_event($this->Stream,$EventID);
$AttributeArray = $event->attrlist;
if (is_array($AttributeArray))
{
foreach ($AttributeArray as $key=>$value)
{
echo " Event['".$key."'] = '" . $value ."';\n";
}
}