Thanks for this, everyone. I've downloaded Sarissa.

Is there a worked example anywhere? The documentation stops at the point
where you want to display the transformation result on the HTML page.
I've worked out how to do this under IE, but not under Netscape.

I had some trouble passing stylesheet parameters, but I think I've fixed
that. It seems the parameter must be defined in the top-most stylesheet
module, not in an imported module. Looking at the code, it seems it
actually modifies the value within the stylesheet DOM!