Formatting multiple subtitles

Hello,

I've got a DocBook document with multiple subtitle elements (bookinfo)
and I'd like to style each of them a bit differently on the recto side
of the title page (by default at least, all the subtitles have the
same formatting applied). I'm mostly looking to tweak font size,
font-weight, etc.

Is there a way I can have indicate different formatting for different
subtitles in the title page spec file (based on
fo/titlepage.templates.xml) or would I need to do my own table layout
for this with a custom book.tiltepage.recto template?

Thanks,
Ken