What I do is put the cat in a room with all his stuff - litterbox, food, etc. and leave him there for about a week. Go and visit him often, and bring something the dogs have been lying on and let him lie on it, then let the dogs sniff it.
After a week, put a baby gate on the door of the cat's room - lifted high enough off the floor so that the cat can get under it, but not the dogs. Then let the cat come out on his own. Cats are much more confident and willing to come out if they know they have a "safe place." If you think your dogs might go over the gate or knock it down, put a couple hooks in the door and the frame and wire it so it opens only wide enough to admit the cat.
Keep your dogs leashed until you know their reaction and if they doesn't know the "leave it" command, I would teach it to them.
NEVER try and force the cat to meet the dogs, and NEVER let the dogs chase the cat!
I have a cat-submissive and friendly dog, but the cats I've introduced to her had never been near a dog, and one of them was an adult feral tomcat. This method always works for me!