The source code of Doom3 BFG is quite clear and seems to be very solid and well structured. That is to say that its use or import into other codebase should be well feasible. We have a strong experience with C++, network transmission and optimization techniques, and in these points we could surely bring you a good help. Game development doesn't belong to our portfolio, although with graphic processing we are also well knowledgeable. We would say according to your description that the task to be done affects mostly the networking part of the engine, that is framework/common_network and its implications into d3xp/game_local, player etc. If that is the case, we could gladly take in charge the assignement. If you consider that could be a solution, please let us know your codebase so that we can evaluate the work to be done. We will then propose you a fixed quote and a time frame for the development.
Regards
The Bramfeld Team