Hehe, I'm this far.

I think I will get some time to play this week too, so I might even finish this game soon.
Yes you have to look in the Chariots of War program files, there will be the Tweaks.txt file and in it there is a place like this:
// 10th's of a % of world to control to win game
WinPercentage 1000
WinClearPercentage 1000
I copied that from my Tweaks file, I think both WinClearPercentage and WinPercentage are at 750 before you change it. And having them both at 1000 will make the game last until you conquer the world.