Different Maps scripts usually do this, A Terra map usually starts on a single continent with a second continent near by, but seeing as they all start in the old world they area is going to get cramped pretty quickly.
Hemispheres usually remain balanced out with each player starting on the same horizontal line depending on the player. Pangea seems to have big amount of space usually. I think it usually depends on the type of map script you are playing, I don't think it is something you can do with an xml file. So, I doubt it.