I'm not sure if this would help since I don't know anything about the cheat system. Brad said in his "did you know" thread that you can play a sort of hotseat game...
#5 You can play a quasi-Hot seat game with someone by loading up the game as GalCiv2 cheat (use the cheat parameter). Then when you set up the game, you let the AI play out a few turns and then have your friend pick one of the races they want to control. Have them select that unit and hit CTRL-SHIFT-Z.
https://forums.galciv2.com/102205
It might also help to know that you can back up your "My Games" folder (or just the related subfolder) and replace it with one that has the hotseat game. You can play a turn and zip the folder, email it and your friend can unzip it and play his/her turn. Then just do the reverse and you have an epic multiplayer game that will keep you in communication for months or maybe years to come.
Keep in mind that the original host's game serial number and email address is embedded in the saved game files, so you should only do this with someone you trust such as a family member or close friend.
If email isn't attractive, a free ftp site might do. I think I used DriveHQ when I needed a temporary free FTP. http://www.drivehq.com/ftp/
Limited, but hey, it's free.
While your friend is playing his/her turn, you can restore your original folder and play some sandbox games or some such thing.