freebsd6 utilities and proxy

[Dave]

Hello,
    I've got a FreeBSD 6.2 machine now behind a squid nontransparent 
authenticating proxy. The proxy use to be transparent and didn't require 
authentication, those requirements now changed, so it now utilizes a 
dedicated ip and basic authentication. This is fine for the machine it's on, 
but for machines behind it this presents a problem. They run freshclam for 
virus updating, csup or portsnap, fetch, and portupgrade and maybe others 
not sure if i remembered them all. Is there a simple way i can configure 
this box to deal with the new proxy?
Thanks.
Dave.