Aug 072013
  1. In file /etc/yum.repos.d/CentOS-Base.repo in section [base] set enabled=1
  2. sed -i 's/enabled=0/enabled=1/g' /etc/yum.repos.d/CentOS-Base.repo
  3. For XenServer 6.2, 6.5 in file /etc/yum.repos.d/Citrix.repo in section [citrix] set enabled=0
  4. sed -i 's/enabled=1/enabled=0/g' /etc/yum.repos.d/Citrix.repo
  5.  rpm -Uvh http://dl.fedoraproject.org/pub/epel/5/$(uname -i)/epel-release-5-4.noarch.rpm
     cd /tmp
     wget https://yum.puppetlabs.com/el/5/products/$(uname -i)/puppetlabs-release-5-10.noarch.rpm
     rpm -Uvh puppetlabs-release-5-10.noarch.rpm
     yum install puppet

    set up /etc/puppet/puppet.conf, after that:

     chkconfig puppet on
     /etc/init.d/puppet start

I Also recommend using a xs_patcher to make XenServer up to date.