The article starts with the basics, XML and JSON, then moves quickly on to other topics like "browser-side data processing" and "xml-to-json conversion". From there, it's all about the code - creating the xml2json script to make the transition simple. It incorporates the Services_JSON package to help with the handling.
The entire code is laid out in one block, making it simple to cut & paste and mess with a bit. They even include a sample of its usage as a command line script, complete with sample input and the resulting output.