Warning : these publications work only with Lenya 1.2. Not sure if they are compatible with 1.2.5, though
Much of the time, it's easier to just look at a real-world working example of a new technology and to reverse-engineer it. Once you're comfortable with just tweaking the default publication on your Lenya installation, you may want to download a more complex working publication. Wyona has been kind enough to make such an example (the University of Zurich publication) available on their .org site.
Please go to http://www.wyona.org and follow the instructions to use SVN to download the publication and move it to your /pubs folder within your Lenya instance. Restart your Tomcat or Jetty (et al) and you should have the new publication available.
There are many examples of creating custom types (a big topic for Lenya newbies), customizing bxe_xpaths to get BXE working with those custom types, customizing XSL files to allow for editing of custom types through the Forms Editor successfully, etc.
Hopefully, the sample publications will allow you to find advanced techniques quickly, while the wiki continues to complete further documentation.