xpath_bool_ns() and xml2

Hi,

does anybody know how to use the xml2 function xpath_bool with namespaces.

I have used this function successfully as long as my xml documents haven't
contained namespaces. I searched with google and found some readme file
where the function xpath_bool_ns was available that would probably resolve
my namespace aware xml xpath issue, but this function isn't contained in the
pqxml.dll that comes with postgres 8.3.3.

Can anybody help me or point some other solution ? I just want to do some
xpath queries on a table column that returns a Boolean as result.

Cheers, Tobias