Network Bridging or forcing specific NICs

Question

So this is a challenging problem, which I have yet to find an answer.
At work we have wired and wireless connections, the wired i use my laptop thru proxy to connect to RDC of a windows server, it also have very restricted internet access. The wireless connection does not need the proxy and I want to set up an internet browser to use the wireless while the RDC uses wired.
Question is, is there any way to force a program firefox or safari to use one interface while others use the other interface. I have tried rearranging the order of service in networks but that just makes the wired services not work.

Answer 1

Per application would probalby require a special proxy running local on the system.
However, per destination is definitely possible.
Set your box back up so that your wireless is the default path since if I understood you correctly, that sends you out direct and what you want for most things.
Open Terminal (spotnight/terminal)
run 'netstat -rn' and get the default gateway for your en0 interface (wired).
add a static route for the proxy that you want to use only over Wired to that gateway.
For instance, if the proxy was 5.4.3.2 and your next hop off en0 is 192.168.1.1, you would enter:
sudo route -nv add -host 5.4.3.2 192.168.1.1