I'm getting a pug beagle mix puppy soon, how do I introduce it to my cats?

[mystic_flower2]

My cats hate dogs, one is a domestic longhair and the other is a norwegian forest cat. They both have bad experience with dogs.
My wedgie is a year old and my longhair is 8. The wedgie was attacked by a pit bull when he was about 6 months old and my longhair was attacked by a rottweiler when she was 4.
They actually aren't my cats, they're my moms, I am getting a little puggle soon, It will be about 6 weeks old. How can I introduce the the cats and the puppy without having any horrible issues.
I chose a pug beagle mix because it was at my local shelter and I decided to put him on hold and adopt him, I'm saving him. I am not buying him from a pet store or breeder.I originally wanted beagle purebred but I also wanted a pug. I've been waiting a long time for a pug beagle mix to be at my local shelter and he's finally there
They're keeping him on hold until he's old enough to be on his own with me :3