The docbookm package is contributed with LayManSys and contains very simple XSLT drivers for generating XHTML chunks from DocBook XML. This package does not require an installation; you only have to unzip the package's contents into a directory of your choice and start using it. There is no special documentation available. Use the file abstract.xsl for transforming an abstract and section.xsl for transforming sections. All other .xsl files are only includes needed by those two.
The goal of xmlportlet is to provide a base portlet to serve as a simple mechanism for transforming XML data into the view for your portlet application. This base portlet will be JSR-168 compliant, and will relieve you from developing the basic boilerplate logic needed to transform XML using XSLT into HTML.