OK, I finally did get this working. It seems that you have to press B and 1 at the exact same moment. Holding B then pressing 1 will not work.
Anyway, it works
Though there are some issues, which I shall list here
--The removing of the health warning screen is very buggy. It still shows up, albeit *very* briefly. Sometimes it will then go automatically to the main menu. Other times it will appear to hang on a black screen -- it turns out in these cases, A needs to be pressed, and you can get from the black screen to the menu.
--The rescue menu doesn't seem to do anything. Sometimes it will display "3.2E" and just hang there. Other times, the "3.2E" will go away, then it will hang. I've tried this with several discs, and no disc at all.
--Its region free implementation is rather buggy. While all PAL games work perfectly, both the NTSC/U games that I own do not work properly.
-Brawl has a black screen for about half a minute, then at the intro movie, it begins to work. (It's in PAL! Good news for owners of RGB cables or rubbish TVs)
-No More Heroes doesn't work at all. The screen goes black and the Wiimote is turned off.