Frustrating because I can't get past even the mySQL installation stage. I don't know if the software package has changed since this was written, but the downloads at http://dev.mysql.com/downloads/ aren't like "mysql-standard-version-osxversion-platform.dmg"...
Anyway I downloaded the x86 version anyways, and installed. The command "$ sudo /usr/local/bin/mysqld_safe5" doesn't do anything. That directory wasn't created by the installation.
All rather annoying as I can't progress until I've sorted this out!
I installed the dmg that makes mysql start automatically every time the computer is started. I then restarted. The program will then run in the background. To get into the mysql prompt it was sudo /usr/local/mysql/bin/mysql -u root -p