Still working on a search form

Well, here’s the thing: To limit custom Google searches to just content from the root of this specific blog, I need to pass the string inurl:0001111 (that’s my Radio usernum) to the form handler on the Google end. I think I need to go back to web forms school, because I’m stymied. As I see it, there are two ways to do this:

  1. Add a hidden form element and pass the value that way
  2. Give the string above as the default value in the form field and tell users to ignore (but not delete) it.

The problem with the first approach is that I don’t know how to make Google concatenate the hidden string with the search terms submitted manually through the form.
The problem with the second approach is that it’s ugly and more than likely the user will end up stomping on the default text.
Is there a third way? Is there some trick to tell custom Google “hey, this hidden value is one of the search terms”? Am I missing something (probably).
The resulting search page also reverts to offering a search of the root domain, so at best this is a half measure until I move my site over to