routing advanced issue - ebtables and bridging

Morning, am new in here.
Just wondering if anyone can suggest me a solution to the following problem.


I got a incoming connection 64.110.x.x , static IP and it goes into the Enterprise-LAN through a proxy(http)called mission control open.ch , locked to this ip.

I want to install a box before the proxy , between the source line 64.110.x.x and the proxy.
I got Ubuntu 11.04 up running on my box with 2 eth cards...

I heard one possibility is to create a brigde between the two lan interfaces so that traffic normally goes straight through, and then use ebtables and nat/proxy-arp to get all the unfiltered the traffic to my box.

Do you know how to implement such a solution in a easy way=?

p.s. the proxy receives “only” the 64.110.x.x address and its locked to it.

Wish you a nice day from Congo.
Hugs
Ugo