1. Install XCODE 4. This is actually trickier than it seems. You have to:

a) download XCode;
b) run the .dmg.
c) quit iTunes, then go into Activity Monitor and force quit on anything iTunes related (iTunesHelper as well);
d) go into the Applications folder and find the “Install XCode” app, and run that. (Yes, you have to run a second Install XCode app…and I had to run it twice. It failed the first time. If you want to watch it fail, drop into Terminal and type this: tail -f /var/log/install.log.

2. Install MacPorts.

3. Test MacPorts by installing joe. Type:

$ sudo bash
$ port install joe.

Enter your password.

4. A bunch of things will be preinstalled with the wrong architecture. We’re trying to get ruby as an x86_64 architecture. So…uninstall libiconv and zlib (you may have to tinker with this a bit because it will ask you which version you want to uninstall — the answer is “all of them”)

$ sudo port uninstall -f libiconv @1.13.1_0
$ sudo port uninstall -f libiconv @1.14_0
$ sudo port uninstall -f zlib
$ port uninstall -f readline
$ port uninstall -f openssl
$ port uninstall -f ncurses @5.8_1
$ port uninstall -f ncurses @5.9_0
$ port uninstall -f ncurses @5.9_1
$ port uninstall -f gdbm

5. Install ruby by doing:

$ port install ruby

7. Update your gems:

$ gem update --system

8. And, finally, install Rails:

$ gem install rails --pre

Useful links:

• http:stackoverflow.com/questions/2916229/how-can-i-install-ruby-on-rails-3-on-osx
• http:beginrescueend.com/rvm/install/