A.E.
It might seem like more work for you but you could try having him clean it up. HElp him get the carpet spray and a rag or sponge. Also make him practice. When he has an accident take him back to the accident make him walk to the bathroom and pull down his pants and practice going potty. Make him do this several times coming from different parts of the house. The potty training book I read suggested 10 practice times. Then go back and clean up the mess and then change clothes.
Good Luck.