Take it slow.
Start off by holding the
kitten in the door way far from your dog. Keep them separated! Every so often bring the kitten closer. This will make the kitten more common and less exciting. Also, give the dog something that smells like the kitten like a blanket or a towel. Let him get used to his smell.
When it's time to bring them face to face, make sure that you pet BOTH of them at the same time. They won't understand that you are petting them at the same time, they will assume you are petting only them, making them feel like they are the ones getting the attention.