Since ferrets generally poop only in corners, if you construct an aparatus
that removes any corners outside the litterbox they will normally go ahead
and get in the box to do their business.
 
We constructed miniature "ramps" outside one litterbox one time, with great
results. Since there were no corners outside the box, the fuzzies jumped
inside to our great self-amusement.
 
Hope that helps!
 
Marcus
 
[Posted in FML issue 0561]