Here is my satiation now:
I am in outside of US. At home I have a router(RT-N16) running tomato. It has two VPN clients setup and both works fine. One of them(let's call it VPNclient2) connected to a server(VPS) located in US. I have root access to the VPS.
Now I want: On PC, make only Firefox connect Internet via VPNclient2 automatically. All other browsers will still use my local ISP.
If above works, I can access Hulu/Netflix and other location restricted services (Google Voice).
I don't want the VPNclient2 get pushed route which will apply on all my local connection.
I don't want manual adding route in tomato every time I want use this route.
So I am think I need a proxy server on my VPS.
Any other(better) advice please?