Im not sure if it's just my copy, but I have only ever been able to get multiplayer Capitalism 2 working one time, when I found the disk by chance in some bargain bin. Since then the disk has been lost, and Im (unfortunately) stuck using a downloaded copy. I dont remember if I had it working online, or through a LAN.
Anyway, perhaps it's too ambitious to request a full scale rework of multiplayer capitalism from an Add-on - but I've often thought about this game having massive potential as a single, world economy massively multiplayer online experience.
At this point I would sell my soul for a good multiplayer match against a single other player!