Although I've never used it, or even know whether this suits your
needs, perhaps the xmpincl package may be of help here. It is
available online via CTAN from
http://tug.ctan.org/cgi-bin/ctanPackageInformation.py?id=xmpincl
The xmpincl package description states the following:
"The XMP (eXtensible Metadata platform) is a framework to add metadata
to digital material to enhance the workflow in publication. The
essence is that the metadata is stored in an XML file, and this XML
stream is then embedded in the file to which it applies. How you
create this XML file is up to you, but the author started
investigating this because he wanted to embed licensing information in
the files he created. The license the author chose is one of the
Creative Commons licenses, and their web-site offers this information
in a valid XML-file, suitable for direct inclusion."
There are other, related LaTeX packages called hyperxmp, and aebxmp.
Search for them on CTAN (
www.ctan.org) and read their description to
see whether they suit you better...or not.
Werner