As far as I understand things, it should be no problem to link two (or more) PC's running the M2 emulator. I.e just add the different IP addresses in the network config files.
By the way, I'm just about to do the same thing. I have plans for doing 2 (or maybe more) down scaled desktop generic SEGA M2 driving cabinets.
Of course, dedicated SEGA Rally and/or Daytona cabinets would have been the best alternative, as long as you have space and money. But how realistic is that?