Hi Matthew,
I found some tutorials on what I believe to be main Xowiki development server. I'm not sure where they are from or what they are for exactly but they helped me, my name also appears in one of them which is nice! They give a good intro to developing with XoTcl and XoWiki.
XoWiki
http://alice.wu-wien.ac.at:8000/s5-xowiki-tutorial/slides
XoTcl-Core
http://alice.wu-wien.ac.at:8000/s5-xotcl-core-tutorial/slides
Appologies if these are the same as the ones on the other link.
Cheers
Matthew
