[squid-users] rewrite domain

Hey everyone,
I'm having problems with rewrite rules.
here is my situation.
I run an Apt Mirror inside my local network, but currently I set my
sources.list to reflect that, but if a laptop leaves the network it
still has that sources.list which is no good due. basically I'm wanting
to rewrite the domain so that it points the
http://us.archive.ubuntu.com/somefolder/somefile.deb to
http://host.localdomain.com/samefolder/samefile.deb

that way the source.list file is valid regardless of location, but
redirects to the local mirror if on the LAN

Any help is appreciated.

-- 
Thomas E. Maleshafske <tmaleshafske_at_maleshafske.com>