I think the problem is that the code is doing a "mysql_select_db" on a connection that vbulletin later tries to use (thinking it's still set to the vbulletin db). You could try to "cheat" by changing the setting to:
Code:
$htdb['datab'] = whatever your vbulletin db is
$htdb['prefix'] = "'X672net_eqdkp.eqdkp_";
This might work (based on a quick glance at the code) and avoids changing code. If it doesn't work you could try changing the code so it doesn't use mysql_select_db but instead puts the database name on each table reference (which you could probably do with a search and replace), and/or use the vbulletin db class instead of calling mysql calls.