[kh99]

Well, I'm not sure if I completely understand. But I don't see why you couldn't copy forum.php to another name, then modify it do display only certain forums. It looks like it uses $vbulletin->forumcache, so maybe near the beginning you could delete the forums you don't want to display from $vbulletin->forumcache. You said you don't want to use mods, but it might be possible to do that in a plugin using hook forumhome_start. You could check for a parameter and adjust forumcache accordingly.

But I haven't actually tried this and sometimes you run in to things that don't work like you hoped, as I'm sure you know.