Yep, I found that earlier when I was looking. Perhaps I should've mentioned it... Oh well, too late now :D.
There is a problem though. That has low level xml parser for odf in general (OpenOffice::OODoc::XPath). Which would enable me to do what I want. However it would be quite a task as it is a low level xml parser for odf. There are some higher level modules in the OpenOffice::OODoc. However the main high level one is for text documents and not for spreadsheets. And that's a problem.
But I hadn't seen that newsletter. Interesting... thanks for that.