Indexing software and DocBook

Has anyone worked with indexing software (like Cindex) and DocBook? It looks like Cindex will operate on XML instances and even export XML, but I don't know how practical it might be to use it for an indexing project in DocBook.

If anyone has experience doing that and could spend a few minutes off-line talking/emailing about it, please let me know.

Thanks,
Dick Hamilton
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