Firstly, thank you for such a nice little macro. Finally, I have a way to integrate docbook into Trac, without having to maintain separate Trac-themed HTML pages. I've two (related) feature requests:
I'm wondering about pagination for large documents. Would it be convenient for the macro to find ?page=123 style arguments from the URI, and pass these through to the stylesheet as <xsl:param> parameters? (These can be programatically bound before executing the stylesheet). I guess it's a bit weird for a macro to pick things up from the request URI, but it seems to make sense in this case.
Another approach would be to pass parameters as extra macro arguments: [[Xslt(..., ..., 'page=1')]] or somesuch. In my case for pagination I'd need to make a separate wiki page per-chapter, though, which wouldn't be nice - but I think passing params here could also be useful in general, for other situations.