Adobe Acrobat allows you to have hit highlighting when a PDF document is
displayed in Adobe Acrobat Reader. The highlight information is passed in
to Acrobat as an xml document that is appended to the requesting url as
shown below:
http://servername/docs/document.pdf#xml=[url_to_xml]
This function returns the contents of the XML document that is to be passed
to acrobat reader. You will need to manufacture the URL on the result list
page to include a page that returns this XML.