Configure SQUID in /etc/squid/squid.conf with:

# squid listen ports
http_port 3128
# set up file system (use aufs or ufs) and directory for caching files, 50000 is disk space in MB which can be used for caching files. 
cache_dir aufs /var/spool/squid 50000 16 256
# maximum object size
maximum_object_size 4096 MB
# memory cache
cache_mem 4096 MB
# Add your local network to your ACLs and other rights depend on your security level. At least to give access for cvmfs clients.
acl local_net src network_addr/mask_addr
http_access allow local_net

wget http://cvmrepo.web.cern.ch/cvmrepo/yum/cernvm.repo -O /etc/yum.repos.d/cernvm.repo
yum install -y cvmfs-keys cvmfs cvmfs-init-scripts

Create directory on local disk where CVMFS client will store data.

mkdir /scr/cvmfs

Edit /etc/cvmfs/default.local. Define some variables:

CVMFS_REPOSITORIES - repositories to include, like atlas.cern.ch or cms.cern.ch.

CVMFS_HTTP_PROXY - URL of your SQUID server

CVMFS_CACHE_BASE - path to data dir

CVMFS_QUOTA_LIMIT - maximum size in MB for cached data. (see http://cernvm.cern.ch/portal/cvmfs/examples)

Bellow is config file we use at ISMA for Belle.

CVMFS_REPOSITORIES=belle.cern.ch
CVMFS_HTTP_PROXY=http://wwproxy.grid.isma:3128
CVMFS_CACHE_BASE=/scr/cvmfs
CVMFS_QUOTA_LIMIT=2000

Add line to /etc/fstab

belle.cern.ch           /cvmfs/belle.cern.ch    cvmfs   ro

Start service

service cvmfs start

Mount FS

mkdir -p /cvmfs/belle.cern.ch
mount -a -t cvmfs

Try ls -l /cvmfs/belle.cern.ch - it should work.