I never used v6 threads.
But if you have a config.inc.php file that holds most of your settings.
In the current versions if you edit the file and at least add in the paths and passwords it will usually let you get to the control panel. Then just go through each option in the control panel and select submit even if it looks correct.
there are a couple of config files posted here but I am not sure how compatible they are with your version since they are for the 7x series.
You also could try ubbdev.com and search for config.inc.php
