here are 2 threads that have excellent humidity solutions:

http://ball-pythons.net/forums/showt...arium-Solution

http://ball-pythons.net/forums/showt...tment-Tutorial

as long as you can keep the humidity between 40% & 60% you will be fine. the only time humidity needs to be higher than that is during shed. During shed try to get it up to 60%-80%

humidity doesn't need to be constant, you can provide "humidity cycles" basically you mist the cage and get it up as high as you can. you then wait until the humidity has dropped to 40%, then mist again