If it's so dry that it is breaking when you move it, then spritzing may be your only choice. Usually I use a humidifier stone or a disc device (available at pipe shops) to moisten the tobacco. I check it frequently and soak the humidifier if needed. Some times I put the dry tobacco in a bag (leaving it open) inside another bag that has a moistened paper towel in it. Seal the outer bag and let the moisture from the paper towel flow to the tobacco. The tobacco does not actually touch the paper towel.