limit indexing / searching based on meta tag

Hello,

I am using the spider.pl method to index a website. I would like to only 
index those pages that have a specific meta tag, i.e.:
<meta name="generator" content="blah blah custom">

So, any page with a meta tag of generator that contains the keyword 
"custom". If I cannot limit the indexing, can I restrict searches to only 
look in webpages that have this specific meta content?

Thanks.

Rob