Controlling source of http with Squid???

Is it possible to use Squid to force one subnet to receive content over one link
to the net and another subnet to receive content through a different link.

The following diagram explains further (Routers not shown)

User Group 1 User Group 2 Proxy(Squid)
Subnet 1 Subnet 2
   | |
|
   | |
|
   ----------------------------------------------------------------------
  | Hub
|
   ----------------------------------------------------------------------
           | |
           | |
  Link 1 Link 2
ISDN 64K ISDN 128K

All web browsers are set to use the proxy server.
This is a small part of a much larger network and as stated above I need Group 1
to source http through Link 1 via the proxy and Group 2 through Link 2 via the
proxy.

Is this possible? Either with Squid configuration or Linux (Red Hat 6.0).

-
Kind regards
Stephen Neander