I'm not 100% sure what your implementation will be but I've done some work in this area.
Take a look at PDFLink.getFoAsString() where I convert a RenderCommand to a String of markup (XML in the example) http://tapestry-stitch.uklance.cloudbees.net/pdflinkdemo Also, take a look at this wiki entry http://wiki.apache.org/tapestry/Tapestry5HowToGetAnHTMLStringFromARenderCommandParameter Note that a Block can be type coerced to a RenderCommand
