I would agree with the above post.
Basic obediance first and let the dogs see you around the ferrets. I have a terrier I am still working on around the ferrets and a year on into I but still wouldn't look away.
May be trying working with the older one first letting him see you handle them, cleaning them out, taking them in and out of boxes and running about and a cage or run so they can meet with safety and if possible feed them together (be very very close and ready to put you hand between, if you do get bite don't squeel the dog will react). Only do a few mins a day and not to over do it. I then went on to the odd tube/pipe and letting the dog see the ferret pop out the hole and re entre and walk along the floor, again relying on site and stay etc.
Then more pipes etc.
Or even take just the older one up the mark up and lead it up away from holes and let him see what happens, be prepared for smaller bags as you or the dog may be a little noiser when you have both learn what the other will be doing.
Take your time and good luck.