To use the syntax higlighting extension with DocBook-XSL 1.74.3+, you must:
1. Use a processor that works with the extension: Saxon 6 or Xalan-J.
2. Add the latest version of xslthl-2.X.X.jar to your classpath.
3. Set the highlight.source parameter to 1.
4. Import into your customization one of the following stylesheet module:
  * html/highlight.xsl
  * xhtml/highlight.xsl
  * xhtml-1_1/highlight.xsl
  * fo/highlight.xsl
5. Use that customiztion layer.


Note: Saxon 8.5 or later is also supported, but since it is an XSLT 2.0
processor it is not guaranteed to work with DocBook-XSL in all
circumstances. 

