Install MySQL gem on 64 bit Snow Leopard

Install 64 bit MySQL then run following commands in terminal:

export ARCHFLAGS="-arch i386 -arch x86_64"</pre>
gem install --no-rdoc --no-ri mysql -- --with-mysql-dir=/usr/local --with-mysql-config=/usr/local/mysql/bin/mysql_config

CREDIT:http://weblog.rubyonrails.org/2009/8/30/upgrading-to-snow-leopard