find a rated game of it and play
4 PC Takeover

Go to 4 Player Chess, click the Edit Rules button, and click Takeover.
If you wish to play this in rated, you will need to (like @1username2awesome3 said) find an old game in somebody's archive (and there's a 99.9% chance that you will have to play Old Setup instead of New)
4PC in the " takeover " mode. Talk about fun
Oh , yeah !!! If this is already available, how do you access it ?