how do I get the perl backend for the documentation wiki

I guess you ask me. I haven't bothered to make it available anywhere because I've been working on it, but I can put up a copy...

http://wakaba.c3.cx/releases/other/kozakana.zip

Just put it in the same directory as the html file (with the modifications I've made relative to the original TiddlyWiki version; best to just copy docs.html or test.html and remove the text from them). The rest should be magic.