[CentOS] dhcp & squid

Everyone,

I have set up squid as a proxy http server in order to filter web access
for an office that wants to block certain web sites.  

Is there a way to use the dhcpd server to assign the squid server and
port number 3128 to each Linux desktop when they boot using the existing
dhcpd server.  Or do I need to change each user's network preference
setup in firefox.   The dhcpd server and squid are on the same server.

I have looked at the man pages for dhcpd, dhcpd.conf, dhcp-options,
dhcllient, and dhclient.conf.  

I found an option :

option www-server ###.###.###.###
 However there was no reference to stipulate a port number like 3128
that is used by squid.

Other searching on the web has uncovered the use of:

option custom-proxy-server "http://192.168.1.1/wpad.pac"
 but I am uncertain as to how to configure wpad.pac file

Any answers or suggestions on reading material would be appreciated.

Thanks,

Greg Ennis