Firstly, installing the newer wmii is a relatively simple task: you'll want to grab the 3.9.2 sources from here (don't check them out of mercurial; it will only make the process more painful for you). Then untar the tbz and issue the following commands in the source directory:
make deb-dep make deb
The deb will be built for you in the directory above, and you can install it at your leisure.
Secondly, configuring wmii could be a simple task, but I thought I'd try out this new fangled Ruby gem for configuring wmii. It was a mistake.
There's no documentation on which version of the gem the bundled config.yml is to work against, nor is it mentioned whether or not I should be using Ruby 1.8.7 or 1.9.1. I would assume that it would work against both, but after hours of suffering through incessant broken pipe errors and trying to optimize the configuration (switching views taking almost half a second - wtf?!), I decided to just go with the bundled wmiirc configuration.
As it turns out, the 3.9 configuration has changed, so my old wmiirc didn't work. Upon closer examination, the changes weren't that huge, and I was able to port my old settings over pretty easily.
You may see them here.
UpdateWoops. I recall the instructions say to do make deb, but that doesn't work. Try this instead:
make deb-dep dpkg-buildpackage -us -uc -b