[support] Dynamic remote database access

I know that the "standard" way to access another database is to include it in $db_url in the settigs.php file. This has the undesireable effect that the remote database must be available all the time. In my case, we only need to access the remote DB a few times a week via a cron job, where much better error handling is available. I haven't yet found a way (I'm still searching DO) to do this. Does anyone have any good ideas? This is Drupal 6 - don't bother suggesting an upgrade. Replication is probably not an option because we shouldn't have access to, nor need, everything in the remote DB.

Nancy   Injustice anywhere is a threat to justice everywhere. -- Dr. Martin L. King, Jr.