I think that if your snake seems constipated, you should give him a good hour-long soak. Just get a rubbermaid container with a secure lid, that is at least half the snake's length on its longest side. Put enough warm (Not hot, but not cold either) water in, and put the snake in there for about an hour, making sure the water doesn't get too cool. Usually you'll find a bowel movement has occured after about fifteen minutes!