I'm not expert with the Lucene search, but I don't think you can search protected content. As good as the Lucene search is, it is not overly configurable.
You can search protected content with XSLTsearch, which does not rely on the Lucene engine. It is suitable for sites of <1000 nodes. By default, XSLTsearch does *not* search protected pages, but this is easily modified (I use the IsProtected function, which you'd just remove from the XSLT).
Search the forum for XSLTsearch for more info on it.
cheers,
doug.
MVP 2007-2009 - Official Umbraco Trainer for North America -
Percipient Studios