NOTE!!! Contrary to what the documentation says, if you are upgrading a 5.x database, you should leave the biblio module enabled during the upgrade.
The way I test upgrades (5.x to 6.x) is to make a backup of your entire 5.x schema and restore it to another schema name. For example, If I have a schema called D5 (which has all the usual drupal and biblio tables) and in settings.php the database line looks something like this...
$db_url = 'mysql://user:password@localhost/D5';
Then I would restore the drupal 5.x backup to a schema called "test". Now I would install Drupal 6.2 in another directory and get it all setup and working (including biblio) and then I would edit the settings.php file in the D6 installation and set the db_url to the newly created "test" schema that contains the 5.x tables restored from the backup. So the D6 db_url line would now be changed from this...
Initial beta release of Drupal 6 module. Thanks to intchanter for the work on conversion from Drupal 5 to Drupal 6 as well as fleshing out many other necessary changes. Likely this will be the only beta before a release unless some significant issues come up.