Seperate internet connections 1 pc.

Ok here's the deal, i play a online game that does not allow multiple clients to be ran on one pc, but does allow you to run multiple clients within same household(for example second pc)... Well i do not have a second pc, and i would like to fool them by running multiple connections in 1 pc through a linksys router giving different mac address..I need to know how to accomplish this task, (* game launcher will only launch one client, but after searching the directory files i was able to find another laucher that does bring up a new client) basically need this client/launcher to access the second connection.. any help would be greatly valued. Regards..