How to generate <!DOCTYPE with ENTITYs> from XSLT

I have an XML document that is rendered in HTML using xslt.  I'm attempting
to write an XSLT that produces an FO document that contains a DOCTYPE
declaration as:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE fo:root [
<!ENTITY nbsp "&#160;">
]>
<fo:root xmlns:fox="http://xml.apache.org/fop/extensions" xmlns:fo="
http://www.w3.org/1999/XSL/Format">


So far, I have not been able to figure out how to generate the DOCTYPE and
ENTITY portion.  Can anyone point me to an XSLT example for how to do this?

Thanks
Michael Giroux