Thanks to a prompt from the fabulous @liminal_andy, I've started making a tutorial file for the Stage Mouse Watcher (it incorporates some brilliant programming of his as well). Here's a sneak peek:
Have you checked out the Body Tracking Guru Session? It comes with a set of files that may prove useful.
The OpenNI Tracker Tutorial file (for the OpenNI plugins) may also be helpful as a starting point.
This forum thread has some helpful work from @bonemap you could try to incorperate.
From the TroikaTronix Add-Ons page, there's also this 3d lines puppet for the OpenNI actors, which is also from the fabulous @bonemap.
You could probably also adapt the work that @mark posted in this forum thread.
Searching the forum for "3D particles" may also turn up other treasures for you :)
What tutorial are you referring to?