This is for software built from source according to:
http://hivelogic.com/articles/installing-mysql-on-mac-os-x/

Start MySQL

sudo launchctl unload -w /Library/LaunchDaemons/com.mysql.mysqld.plist

Stop MySQL

sudo launchctl load -w /Library/LaunchDaemons/com.mysql.mysqld.plist

You have to symlink mysql to the location on osx

first find out where mysql has put the socket:

mysql_config5 --socket

Next symlink /tmp/mysql.sock to the right location of the socket

sudo ln -s path-of-mysql.sock-from-above /tmp/mysql.sock

Start MySQL

sudo /opt/local/share/mysql5/mysql/mysql.server start

or

/opt/local/bin/mysqld_safe5

Stop MySQL

sudo /opt/local/share/mysql5/mysql/mysql.server stop

Go to terminal:

sudo apt-get install apache2 mysql-server php5 php5-odbc libapache2-mod-php5 php5-xsl php5-gd php-pear libapache2-mod-auth-mysql php5-mysql libmyodbc

Now hand edit (or create, if it does not exist already) /etc/odbc.ini

Here's an example odbc.ini:

[ODBC Data Sources]
odbcname     = MyODBC 3.51 Driver DSN

[odbcname]
Driver       = /usr/lib/odbc/libmyodbc.so
Description  = MyODBC 3.51 Driver DSN
SERVER       = my.database.server.com
PORT         =
USER         = USER
Password     = XXXXXX
Database     = DBNAME
OPTION       = 3
SOCKET       =

[Default]
Driver       = /usr/local/lib/libmyodbc3.so
Description  = MyODBC 3.51 Driver DSN
SERVER       = localhost
PORT         =
USER         = root
Password     =
Database     = test
OPTION       = 3
SOCKET       =

Remember to start and stop mysql and apache:

sudo /etc/init.d/mysql start
sudo /etc/init.d/apache2 start

sudo /etc/init.d/mysql stop
sudo /etc/init.d/apache2 stop
sudo /etc/init.d/mysql restart
sudo /etc/init.d/apache2 restart

mysql -u root -p (your password)

then write the following

GRANT ALL PRIVILEGES ON *.* TO user@'%' IDENTIFIED BY 'PASSWORD';

then

FLUSH PRIVILEGES;

If you already have MySQL installed and used the package installer from MySQL to install it, you need to remove a single file (actually a symlink) to disable it:

sudo rm /usr/local/mysql

If you also installed the StartupItem package, you’ll want to remove it as well. Keep in mind that if you ever want to auto-start the old version of MySQL later on, you’ll need to re-download the package installer and reinstall the StartupItem.

sudo rm -rf /Library/StartupItems/MySQLCOM/

mysql -h localhost -u root
mysql> USE mysql;
mysql> UPDATE user SET Password=PASSWORD('root-pwd') WHERE user='root';
mysql> FLUSH PRIVILEGES;
mysql> EXIT

mysql> GRANT ALL PRIVILEGES ON *.* TO 'user'@'localhost'
    ->     IDENTIFIED BY 'some_pass' WITH GRANT OPTION;

A startup item has been generated that will aid in starting mysql5 with launchd. It is disabled by default. Execute the following command to start it, and to cause it to launch at startup:

sudo launchctl load -w /Library/LaunchDaemons/org.macports.mysql5.plist

#starting SQL:

sudo /usr/local/mysql/support-files/mysql.server start

Stoping SQL:

sudo /usr/local/mysql/support-files/mysql.server stop