Just copy the below lines into a shell as root and your done (optionally reboot if you want to get rid of the ipv6 module as well:
cat >> /etc/sysctl.conf << EOF
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
EOF
sysctl -p
cat >> /etc/sysconfig/network << EOF
NETWORKING_IPV6=no
IPV6INIT=no
EOF
cat >> /etc/modprobe.d/blacklist.conf << EOF
blacklist net-pf-10
blacklist ipv6
EOF
echo "install ipv6 /bin/true" > /etc/modprobe.d/ipv6_disabled.conf
sed -i -e s/rd_NO_DM/rd_NO_DM\ ipv6.disable=1/ /etc/grub.conf