Well that was dead simple. Those guys are really great, breaking it all down into five easy steps so it only took half an hour and that was deliberating each step carefully.
Now I really need to update the theme. I hacked the default one and I see that the upgrade made a few changes to that as well. This reveals a well known rule of programming—documentation only gets done on the first revision when you can’t remember how it works.
Unfortunately the upgrade hasn’t stopped the spam so phase two will be getting to grips with plugins.