$ sudo a2dissite site_name
$ rvm --default use ree (be specific as possible about the version)
$ sudo a2dismod passenger
$ gem install passenger --no-ri --no-rdoc
$ passenger-install-apache2-module
$ sudo vim /etc/apache2/mods-available/passenger.load and change path to reflect REE per Passenger module post-install instructions
$ sudo vim /etc/apache2/mods-available/passenger.conf and change path to reflect REE per Passenger module post-install instructions
$ sudo a2enmod passenger
$ sudo a2ensite site_name
$ sudo /etc/init.d/apache2 restart
follow instructions from a2enmod to restart apache, which will also reload site configuration
test the site