How to downgrade rails version in Max OS X Snow Leopard?

I have Mac OS X Snow leopard that has pre-installed Ruby 1.8.7 and Rails 3.0.1 I need to work with Redmine a bit that requires Rails 2.3.5

Is it possible to correctly downgrade my current rails 3.0.1 t开发者_C百科o rails 2.3.5?

You don't need to downgrade, RubyGems allow you to install multiple versions of the same library.

$ gem install rails -v 2.3.5

To avoid versioning hell, you can also use rvm, which allows you to install multiple ruby versions and "gemsets" on the same machine and switch between them.