This was not an easy install; thanks for the great resource. I'm pretty sure I'd have ditched MacPorts without a guide (just not worth the trouble). Nonetheless, I still ran into some trouble with the socket.
For whatever reason, my install expected the socket to exist as /opt/local/var/run/mysql5/mysqld.sock (not /tmp/myslq.sock). The only way I could get it to work was to create the socket it expected.
$ touch /opt/local/var/run/mysql5/mysqld.sock
Then, once I deleted the contents of my my.cnf file, I was able to connect.
Thanks again.