A brief guide:

1. Install ruby and passenger dependencies

   yum -y install ruby zlib-devel curl-devel openssl-devel httpd-devel apr-devel apr-util-devel mysql-devel

2. Install gem

   wget http://production.cf.rubygems.org/rubygems/rubygems-1.8.17.tgz
   tar zxvf rubygems-1.8.17.tgz
   cd rubygems-1.8.17
   ruby setup.rb

3. Install and build a Passenger for Apache

   gem install passenger
   passenger-install-apache2-module

4. Create passenger.conf file in /etc/httpd/conf.d

   LoadModule passenger_module /usr/lib/ruby/gems/1.8/gems/passenger-3.0.11/ext/apache2/mod_passenger.so
   PassengerRoot /usr/lib/ruby/gems/1.8/gems/passenger-3.0.11
   PassengerRuby /usr/bin/ruby

5. Create conf file for your Rails application
6. Temporarily go into SELinux permissive mode

   setenforce 0

7. Restart Apache

   /sbin/service httpd restart

8. Start using your Rails application
9. Walk through SELinux log and generate new SELinux policy module

   grep httpd /var/log/audit/audit.log | audit2allow -M passenger

10. Install newly created SELinux module

    semodule -i passenger.pp

11. Switch SELinux back into enforcing mode

    setenforce 1