Have you considered a client-side library to do the work of highlighting the search text when the page is rendered? I think that it is how most operate.
You would use a javascript library (like jQuery, Prototype, etc) to apply a class to word that meet the search criteria.
You can find plugins to do the heavy-lifting, such as this:
http://bartaz.github.com/sandbox.js/jquery.highlight.html[
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Cheers,
-jc
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