I've installed and reinstalled MySQL with the following command line:
    $ sudo port install mysql5 +server

Initially, I had trouble creating the initial mysql database because the /opt/local/temp directory did not exist (and therefore the /opt/local/temp/mysql5 directory did not exist).

Creating these two directories, and making the mysql user the owner of /opt/local/temp/mysql5 allowed me to build the initial database, but sadly it had no data in any of the non-index tables.

I went ahead and unistalled mysql5 and reinstalled it, and now I get the following when I try to change the root password:
    $ mysqladmin -u root password 'newpass'
    mysqladmin: connect to server at 'localhost' failed    error: 'Can't connect to local MySQL server through socket '/opt/local/var/run/mysql5/mysqld.sock' (2)'    Check that mysqld is running and that the socket: '/opt/local/var/run/mysql5/mysqld.sock' exists!

I verified that mysqld is running through the Activity Monitor.

Sure enough, /opt/local/var/run/mysql5/mysqld.sock does not exist.  In fact, mysqld.sock does not exist anywhere on my hard drive, a fact which I determined by:
    $ sudo find / -name "*.sock"

Elsewhere, I found an instruction to
    $ touch opt/local/var/run/mysql5/mysqld.sock

This command creates an empty file of the correct name; however, when I tried to change the root password, I got:
    $ mysqladmin -u root password 'newpass'
    mysqladmin: connect to server at 'localhost' failed
    error: 'Can't connect to local MySQL server through socket '/opt/local/var/run/mysql5/mysqld.sock' (38)'    Check that mysqld is running and that the socket: '/opt/local/var/run/mysql5/mysqld.sock' exists!

Note that only the error number changed.

When I stopped and restarted mysql5:
    $ sudo launchctl unload /Library/LaunchDaemons/org.macports.mysql5.plist
    $ sudo launchctl load -w /Library/LaunchDaemons/org.macports.mysql5.plist
I found that the mysqld.sock was deleted from opt/local/var/run/mysql5/

Does anyone have any ideas about what I'm supposed to do to get a properly functioning MySQL5 installation?

Environment:
    MacPorts version 1.600.  I've done a selfupdate before attempting to install MySQL5
    Power Mac G4
    Mac OS X 10.4.11