To set up a KML feed in Drupal all you need to do, after downloading the latest Drupal 5 version of KML module, is create a new view, enable the 'page' display for that view and choose 'KML feed' as the format to display. You can then filter it by anything you wish, sort it in different ways and feed it arguments to filter it down even further on the fly (untested, but should work).
If you want to use that feed as a self-refreshing network link, point the user at http://www.example.com/kml/view/<viewname>/networklink
I haven't had a chance yet to test it all thoroughly but it appears to work just fine. Any feedback and testing appreciated though, as always.