Suppressing hyperlinks in PDF

I generate both HTML and PDF versions of my DocBook document.  Most of 
the hyperlinks go to the HTML version of another [non-DocBook] manual. 
This is fine for the HTML version, but in the PDF these hyperlinks come 
out as URLs in brackets, which don't point to the right location even if 
they were clickable, because I move the finished PDF from where it is 
generated.

Therefore, I'd like to suppress the generation of hyperlinks in the PDF, 
somehow.  I imagine you could do this by overriding the rule in the 
fo/docbook.xsl stylesheet that passes the hyperlink info on to the FO 
file.  I know how to do an override, but I don't know _what_ to override 
to make this happen.

For what it's worth, I am using FOP to go from the FO file to a PDF. 
Perhaps there is a way to make FOP do this instead, but it seems cleaner 
to do it by modifying/overriding the stylesheet; that's what stylesheets 
are for, after all, correct?