OT: software to force the client to use the proxy

[Al - Image Hosting Services <azick@xxxxxxxxxxxxxxxxxxxx>]

Hi,

I am using squid with a block list. It works great for everyone on the 
LAN, but the issue that I am not able to effectively filter the internet 
for anyone who is not on the LAN without putting in some proxy settings. 
Is there software that could automatically set this up and lock the 
settings when not on the LAN?

Best Regards,
Al