$ sudo gem install rails --source http://gems.rubyonrails.org --version 1.99.0
Password:
Bulk updating Gem source index for: http://gems.rubyonrails.org
Install required dependency activesupport? [Yn] Y
Install required dependency activerecord? [Yn] Y
Install required dependency actionpack? [Yn] Y
Install required dependency actionmailer? [Yn] Y
Install required dependency activeresource? [Yn] Y
Successfully installed rails-1.99.0
Successfully installed activesupport-1.99.0
Successfully installed activerecord-1.99.0
Successfully installed actionpack-1.99.0
Successfully installed actionmailer-1.99.0
Successfully installed activeresource-1.99.0
Installing ri documentation for activesupport-1.99.0...
Installing ri documentation for activerecord-1.99.0...
Installing ri documentation for actionpack-1.99.0...
Installing ri documentation for actionmailer-1.99.0...
Installing ri documentation for activeresource-1.99.0...
Installing RDoc documentation for activesupport-1.99.0...
Installing RDoc documentation for activerecord-1.99.0...
Installing RDoc documentation for actionpack-1.99.0...
Installing RDoc documentation for actionmailer-1.99.0...
Installing RDoc documentation for activeresource-1.99.0...
$ fastri-server -b Building index. Indexed: _ 7710 methods _ 1364 classes/modules Needed 1.628137 seconds