gem install mysql2 -v 'x.x.x' -- --with-mysql-config=/usr/local/Cellar/mysql/y.y.y/bin/mysql_config
x.x.x = version of the mysql2 gem you want to install
y.y.y = the version of mysql you have installed ls /usr/local/Cellar/mysql to find it.
gem install mysql2 -v 'x.x.x' -- --with-mysql-config=/usr/local/Cellar/mysql/y.y.y/bin/mysql_config
x.x.x = version of the mysql2 gem you want to install
y.y.y = the version of mysql you have installed ls /usr/local/Cellar/mysql to find it.