Does anyone know how to train ferrets?

Ferrets are picky, sometimes they don't like certain litters or they'd rather sleep in them. I had to try a few different types/brands before I found one they would use instead of sleep in. If you catch them in the act, pick them up and put them in the litter box to finish their business, eventually they will catch on. It takes a lot of work but it can be done with persistance. Also, don't leave the litter completely clean. Leave some "evidence" for them to know where to go. They like corners, ferrets will always back up into a corner to go. If they are going on your floor in the same spot put something there to block the corner or you can try vinegar, it is suppose to work as a reppellent. If you can't use vinegar on whatever the surface is you can also try baking soda and water which will get rid of the smell and deter them as well. Don't use cat litter as it gets stuck in their paws and can also cause intestinal blockage if they lick thier paws. Try to get a ferret specific litter if you haven't already, I have found that 'Yesterdays News' ferret litter works best and mine do not sleep in it. It is safe, not too expensive, and is a good odor fighter. If I think of anything else to help you out I'll get back to you.=)