[kh99]

I think there is an article on using data managers in general (although I can't find it right now - I don't think it has "datamanager" or "data manager" in the title). Anyway, probably the easiest thing would be to find code that does what you want and use that. For changing the user's main group, it would be something like:

$userdata =& datamanager_init('User', $vbulletin, ERRTYPE_SILENT);
$userdata->set_existing($user);
$userdata->set('usergroupid', $newgroupid);
$userdata->save();

where $user is an array that has to contain some of the user's data (at least the userid, I think). There's also an issue with user titles - if changing the usergroup would change the usertitle, then you'd have to do that as well (but I guess if the mod you're using isn't doing that now, then you wouldn't have to worry about it).

You might try asking the mod author about it, in the mod thread (if he or she is still around).