This being perlmonks and all i tried to think of a perl based solution but couldn't come up with one off the top of my head that would just plug in and work. Veering away from perl the search engine i have had the most luck with is htdig check out the website i believe it does html and xml files. It is very speedy on my site at least. And it is free in both ways.
Barring that you could always use google to search your site but unless you pay $$ it will take visitors away from your site. My $.02

BigGuy
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