I recently did a switch from enterprise to ruby 1.9 on our servers. I built it from source following this guide: http://www.server-world.info/en/note?os=CentOS_6&p=ruby19
Please be adviced though that the plugin in interworx doesn’t support the latest versions of rails or sqlite. use the following commands to install the rest of the stack:
gem install rails --version 2.3.9
gem install rake
gem install --version 1.2.5 sqlite3-ruby
gem install mysql
gem install passenger