There is a utility called saveconvert. It's an .exe file made by someone here at CFC. It allows you to do things like change a PBEM into a Pitboss, or change an SP game into MP. You can change the type of turns (simultaneous or normal) and you can, alter the length of the turn timer clock.
It's built so that you can't cheat (it won't turn an MP game into a SP one, or let you change a game without the Admin password), and it's very easy to use.