This addon isn't being developed anymore, but still works by changing addon.xml's python requirement (2.0 --> 2.1.0) and having wicd (wicd-curses) installed (on Linux) and removing network-manager. If you're new to wicd and trying to get it working right: run wicd-curses, Preferences > Advanced, then change from wext to nl80211.
... It doesn't close properly, and the stop auto messes things up.
There's a successor addon called 'Network-Manager front-end for XBMCbuntu' but I couldn't get it to work right, so this one is what I'm going with.