Cats are territorial so your kitty would need to feel secure in his territory at home.  Make sure that there are areas that your cat can go that is off limits to the dog.  Perhaps confine the cat to the house for a week just to reinforce this.  Give him lots of attention and reinforce to him that the house is still his territory. 

Malcolm was not too happy when Max moved in. He is 18 and has never lived with a dog before or met one. At first we kept them apart as Max wanted to play with him. Malcolm would come in the lounge in an evening and Max had to stay in the kitchen as I didn't want Malcolm to feel pushed out. Gradually we introduced them to each other. And now they both come into the lounge and go outside at the same time. The other day they were both trying to eat the same blade of grass. It took about 5 weeks to do this but it was worth the effort.