get the ferret in your hand and sit on the floor let the pup have a sniff etc.if he want's to bite the ferret. give him a tap on the nose and a firm no.let them share some food.
no good having either behind mesh looking at each other.it will frustrate the dog no end.
handle the ferret for a few min's untill your hand's smell of ferret then rub your hands all over the dog's head especially around his muzzle nose etc.
so he is continually having the smell of ferret going up his nose.
but the no1 thing to do is keep everything chilled out and relaxed and nice and quiet and cal