Modern Warfare 2 Proxy

i need to setup a proxy for modern warfare 2 so that i can join my brothers game. he is in the same house and we wont let us connect to our same IP address in-game.
Answer #1
but you guys dont have the same ip.
Answer #2
but you guys dont have the same ip.
We have the same internet IP from the router.
Answer #3
My only idea would be to bridge the connection. You would share the internet from a computer (which would have a proxy) with your console. In theory it should work. It would be pretty to simple to setup, all you need is two NICs and something to run your IP through a proxy (this would be the difficult part in my opinion).
Here is a diagram:

(The diagram is a little off, I’m half asleep)
I guess I didn’t think about it, but you could be on PC. So this could all be useless. You should specify what it’s for.
Answer #4
we are both on computer