For all my fellow CentOS/RHEL users here is a quick bash script for getting it running (assumes you don't have ruby 1.9 installed).

    # Install RVM and Ruby 1.9.3
    curl -sSL https://get.rvm.io | bash -s stable
    source /etc/profile.d/rvm.sh
    rvm install 1.9.3

    # Install JSON gem
    gem install json

    # Install Scout realtime
    gem install scout_realtime

    # Start Scout realtime
    scout_realtime

    # Punch a hole in iptables on port 5555 for Scout realtime
    iptables -A INPUT -p tcp --dport 5555 -j ACCEPT
    service iptables save
    service iptables restart