Rails 4 edge install on mt lion

Question

How do I install rails 4.0, bleeding edge (master branch on git) on my Mac? Can I do it with RVM?

I'm doing this to start upgrading a project, not a new project.

Answer 1

rails 4 is coming!!!

gem install rails --version 4.0.0.beta1 --no-ri --no-rdoc

Answer 2

In your gemfile:

gem 'rails', :git => 'git://github.com/rails/rails.git'
gem 'arel',  :git => 'git://github.com/rails/arel.git'
gem 'rack',  :git => 'git://github.com/rack/rack.git'