[kh99]

Maybe you could try this mod: https://vborg.vbsupport.ru/showthread.php?t=172989

or you could try this plugin code:

if (!$vbulletin->userinfo['userid'])
{
   $vbulletin->url = 'custom page url';
   eval(print_standard_redirect('no permission'));
}

using the error_nopermission hook (replacing 'custom page url' with your page url of course). I did a brief test, but you'd want to test it more if you try using this.