Theorems and xref

Hi,

I saw about two weeks ago at docbook.misc group this thread:
http://article.gmane.org/gmane.text.docbook.misc/4329/match=something+like+latex+theorems

I'd like to know if it's possible to use xref so the autogenerated number
can appear somewhere later as a hyperlink to that theorem?

Which stylesheet template I must change?


Thanks.