1. Install XCode (Compatibility: OS X 10.8.4 or later)
  2. Install the source code control system git.
  3. Install the package installer homebrew.
  4. Install a newer version of Ruby than the one that comes with MacOS. This is a nice tutorial for installing ruby. You'll end up with RVM, XCode, and eventually Ruby version 1.9.2.
  5. Install Capistrano: 
    gem install capistrano -v2.15.5
gem install capistrano-ext