OK, thanks for that link.
However, things have not improved. Indeed, the first page of your link provides the same advice to get wireless to connect on boot as I gave in my first post but I still can't get this to work
I tried also many of the suggestions in the wifi section (4.3) of this guide http://gentoo-wiki.com/HARDWARE_Apple_MacBook
but always with the same negative result.
Actually, I have the feeling now that because I have tried so many things to get wireless to connect at boot, I probably have some conflicting commands/instructions on my system. Maybe it's time to clean up everything, and start afresh. However, I'm not quite sure how to do this wihout totally messing up my network configuration.