[kh99]

If you want the value from the current user (the one viewing the page), then you don't have to do anything - the value will be $vbulletin->userinfo['fieldX'].

If you want the value for another user, then you can call fetch_userinfo(), like:

$userinfo = fetch_userinfo($userid);

and the value will be $userinfo['fieldX']. At some hooks (like ones associated with display a user's profile), the value might already be in $userinfo[].