i think he means this:
PHP Code:
$this->validfields['foo'] = array(TYPE_UINT, REQ_NO);
$this->validfields['bar'] = array(TYPE_UINT, REQ_NO);
no you can use $vbulletin->userinfo['foo'] in the script
so the background
1. in the usertable add the columns bar, foo
2. add plugin at the hook userdata_start
now you can use it
i hope it can be understand, sorry for bad english