How to embed XML transforms into Docbook

Hello,

I am fairly new to Docbook and XML, so thanks for your patience.  I have
what is probably a trivial question:

How can I embed XML content into a Docbook from an XML file that contains
non-Docbook entities?

I have created an XSL file that defines a transform of the XML file's
content into a valid Docbook entity.  Can I use an ENTITY declaration (or
another mechanism) in my Docbook file that would embed the transformed
content of the XML file by referencing the XML and the XSL file?  I would
like to do this dynamically, without having to create a file containing the
transformed XML.

The only examples I could find of dynamic transformation of XML, were
transforms to XHTML by a web browser by adding a stylesheet reference in the
XML file, itself.  In my case, the XML file does not "know" that it is going
to be transformed into a Docbook entity; but rather, the Docbook knows that
it wants to transform an XML file into a Docbook entity using a stylesheet.

Any ideas?

Thanks and Regards,

-Jim Kring