Varnish installation on Centos server is very simple :
1. Installing varnish and packages:
mk /root/varnish
cd /root/varnish
wget http://repo.varnish-cache.org/redhat/varnish-3.0/el5/x86_64/varnish-3.0.3-1.el5.centos.x86_64.rpm
wget http://repo.varnish-cache.org/redhat/varnish-3.0/el5/x86_64/varnish-libs-3.0.3-1.el5.centos.x86_64.rpm
rpm -ivh *.rpm
yum install libedit -y
Note: Current installation for x86_64 system also if libedit was not found in your repo, do wollowing:
rpm -ivh http://mirror.chpc.utah.edu/pub/epel/5/x86_64/epel-release-5-4.noarch.rpm