My setup is as follows :
Ubuntu workstation set up as a Squid3 proxy server and DHCP server for LAN.
Proxy IP is :3148 ( Squid3 runs on port 3148 )
Apache webserver running on ( Apache runs on port 81 )
Single network subnet
Single Lan card.

Can I summarise what I think I have to do to achieve all users to automatically route thru the proxy.?

Make a text file with the following content and call it "wpad.dat" ( without the quotes )
function FindProxyForURL(url, host) { return "PROXY; DIRECT"; }
Upload this file to the root directory of the apache server .

Apache Server
1. Create .htaccess file.
2.Add the below line into the file:
AddType application/x-ns-proxy-autoconfig .dat
3. Upload file to same location as wpad.dat file.

Linux DHCP:
1. Edit the DHCP configuration file (/etc/dhcp/dhcpd.conf).
2. Edit and paste the following into the file:

option local-pac-server code 252 = text;
option local-pac-server "";
The first declaration must go in the global section of the configuration file.

3.Restart the DHCP server.

Does this about cover what I must do ?