# Install EPEL
rpm -Uhv http://url/to/epel-release.rpm

# Install the Kolab Groupware repository configuration
cd /etc/yum.repos.d/
wget http://obs.kolabsys.com:82/Kolab:/3.2/CentOS_6/Kolab:3.2.repo
wget http://obs.kolabsys.com:82/Kolab:/3.2:/Updates/CentOS_6/Kolab:3.2:Updates.repo