You will need to install Impulse on each machine and use the installation archive. (Make sure to use the "Download and archive" option in Impulse to transer to other operating systems.)
Just a warning for anyone considering this. In order to get the download and archive option, you have to remove Demigod and download it again. DO NOT DO THIS IF YOU WANT TO PLAY THE GAME SOON. I just tried, and after letting it download overnight, I tried to get my installation back by using "Restore Archive". I got an error that "the archive cannot be restored" or somesuch. I promised some guys at work that I would show them how the game played after hours today, and if I can't run the game at all that won't work. 
Luckily, I made a backup copy of the game, so I copied it back it still runs ... even if it's just single-player that's enough for a demo. Too bad, I was just trying to get a second copy so we could set up a LAN game, if anyone else had a laptop on them.
(I assume this is just a bug, so eventually it will work as promised, but as of this message it is broken and you will waste a lot of time and bandwidth trying to fix it)