I had some issues installing mysql on my upgraded 64 bit snow leopard mac.
Here’s how I got it to work after some pain.
1. Make sure you have http://www.macports.org/install.php
Get the Snow Leopard version (need Xcode and X11 installed before using macports)
2. Install mysql and server with macports
sudo port install mysql5

sudo port install mysql5-server

3. Run mysql install [...]