There's no way. Some progress is being made on analyzing the save game format, but not enough to alter the map.
But don't worry. Coal is likely to show up on one of the squares your laborers are working on.
It might just be that you can't see any coal. Go to your Trade Advisor and talk with other civs and see if they have any coal. If not, then you're all at the same disadvantage. But if there's just one guy who has all the coal, then the rest of you all are probably in a bad situation.