dhcpd proxy and/or windows autoupdates

[wintermutecx at gmail.com (Dave)]

At one of our sites we have most outgoing ports blocked and everyone
going through squid for web access. But it seems Windows autoupdate
doesn't pick up the local users proxy settings so we ended up opening
port 80 to some of the windows update servers.

While searching around I found and option called custom-proxy-server
but I don't see that setting in the man pages. Anyone have experience
setting proxy server settings in dhcpd?