Pete put keys to keyboard and outlines the steps here.

Here are all the commands you need to run in the Terminal to install Ruby, MySQL, and Rails:

sudo port install ruby
sudo port install rb-rubygems
sudo port install msyql5 +server
sudo mysql_install_db5
sudo launchctl load -w /Library/LaunchDaemons/org.macports.mysql5.plist
sudo port install rb-mysql
sudo gem install -y rails
sudo gem install -y mongrel

Check out the article for more details, such as how to set up your environment so the commands above actually work.

If you are on Leopard, Rails is already installed. So you can skip the above steps entirely and just start with:

% rails 

Update: See also this Apple article.

Posted by Geoff Wilson in: Apple, Web Services, Technology