There are a few unfinished or partially functional network plugins for CC around the place... probably the most common/finished one is a plugin by scidave, though it suffers from a few packet leaks and other issues that make it ultimately a little unstable.
Arsonide was working on something, a plugin that used the Raknet library. He got that to a nice working state, but I'm unsure if it was ever released? We were testing out 2-3 connections with about 500 AI server controlled objects... and it ran pretty smooth.
Maybe you can try to PM Arsonide and see if he has any news :)
~Sol