Incorporating search results into vbulletin search

[Reeve of shinra]

I think I understand what you are getting at...

In the forum manager set:
Forum is Active = NO
Forum is Open = YES
Index New Posts in Search Engine = YES

The forum should not appear on the forum list but new posts will show up when they click New Posts.

edit to add:

There are code snippets around here somewhere that will tell you the syntax for having a query search one forum id only. You could add that as a "query form" on your external script but it would pass the request to the forums as if someone decided to enter the url syntax themselves.