Install rails 4.0 with ruby 2.0.0 using RVM & brew

rvm_ruby2_rails4_example.txt

# important update xcode to 4.6 and make sure command line tools are installed under preferences

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

# if brew is already installed update existing
brew update
brew tap homebrew/dupes

# For rvm:
brew install bash curl git

# For ruby:
brew install autoconf automake apple-gcc42 libtool pkg-config openssl readline libyaml sqlite libxml2 libxslt libksba

# Keep it clean
brew upgrade
brew cleanup --force

# fix any issues and make sure you get "Your system is raring to brew." before moving forward
brew doctor

# install rvm
curl -L https://get.rvm.io | bash -s stable --ruby

mkdir -p rails4projects && cd rails4projects

rvm --create --ruby-version ruby-2.0.0@rails4projects

# reload your ruby/gemset that you just created
cd .. && cd -

gem update --system
gem update

gem install rails --version 4.0.0.rc1 --no-ri --no-rdoc

rails new example_app