The INSO libraries are for the Oracle version only, and you need the intermedia search license whcih adds even more cost to a basic oracle setup.
I have previously used the wvWare command line tools with success (http://wvware.sourceforge.net/), though not with OpenACS.
There are some useful looking openacs.org threads mentioning wvware:
http://www.google.com/search?q=site%3Aopenacs.org+wvware
Interesting sidenote: google feeling lucky for "word to html" gives you a page on philip.greenspun.com :)
