Although this does not help the original poster BS - try Happy Search - and use the Google option to add your stand alone site to your XOOPS based ones.
Actually the original poster should try this module as well... Google may pick up the results better then the normal search.
However, I would recomend you do a full dbase + site backup first... or perhaps try doing a test update on a site copy, on your own machine, using XAMPP or something similar.