For example it would help to know what you meant by "use". What do you want to do with this JSP header file? Do you want to write it to the output of the XSLT? As text or XML? Or is it supposed to somehow include some XSLT templates?
And when you say "JSP header file" do you actually mean the raw JSP, or do you actually mean the HTML (or whatever) which results from evaluating the JSP on the web application server?
I'm sure there's more questions to ask about this. Please TellTheDetails.