Processing table entries as "column row"

Hi all,

I'm trying to change the processing of table columns whose corresponding
colspec element have an align="center" value (in particular, I want to
add a grey background to the entry elements). I've tried to unwind how
the DocbookXSL 1.73 stylesheets process these things and it's an
absolute maze of nested template calls. Can anyone shortcut this for me
and point out the appropriate template to modify?

Thanks,
Jeff.