1) Install latest XCode

2) Install the "Command Line Tools for Xcode"

3) ruby -e "$(curl -fsSL https://raw.github.com/mxcl/homebrew/go)"

4) brew install autoconf automake libtool pkg-config openssl readline libyaml sqlite libxml2 libxslt libksba

5) brew install https://raw.github.com/Homebrew/homebrew-dupes/master/apple-gcc42.rb

6) curl -L https://get.rvm.io | bash -s stable

7) source /Users/you_user/.rvm/scripts/rvm

8) rvm pkg install openssl

9) rvm pkg install yaml

10) rvm install ruby