transparent integration with proxy on router

[Todd Nine <todd@xxxxxxxxxxxxxxxxxx>]

Hi all,
 I'm using squid on a pfSense router we've built.  We have 2 
connections, one we pay for usage (DSL) and one we do not (Wireless).  
We use Amazon S3 extensively at work.  We've been attempting to route 
all traffic over the wireless via an IP range, but as S3 can change IPs, 
this doesn't work and we end up with a large bill for our DSL.  Is it 
possible to have squid route connections via a specific interface if a 
hostname such as "amazonaws.com" is in the HTTP request header?

Thanks,
Todd