Someone mentioned putting your rats in a hamster ball but this a TERRIBLE idea. Hamster balls for meant for just that, hamsters. If you put a rat in the ball one of two things will happen. Either the rat will hate it and sit there and get pissed at you, or the rat will try it out and end up damaging its own spine. Either way, it is just a bad idea. DON'T do it.
Now then, an actual "introduction" between adult cats and baby rats is a no-no. The first thing on your agenda should be letting your new rats get used to their new environment. Give them time to settle in and bond with you. Put their cage a couple feet off the ground, like on a dresser, so they can get a good view of their surroundings. After a couple days you can let your cats check out the rats with cage bars between them. Look at their reactions, and if they seem hostile remember to shoo them away whenever you see them eying the cage in the future. If they seem to not really care, you can let them hang out around the cage if they want, but just shoo them away when you open the cage door to feed the rats, and make sure to kick them out of the room for an hour or two when it's time to let the rats out to play. Once the rats get bigger and become accustomed to the sight and smell of cats, you might try taking the rats out and putting them on your shoulders or in your pockets while the cats are in the room and see how they react. If they get curious, allow them to only come within about two feet of you. If they come any closer shoo them away. After a couple of times they should get the idea. But if they don't really pay you any mind, you can set the rats down on your bed (making sure that the cats are on the floor) and keep yourself between the two. If they seem to go into predator mode, put the rats back in the cage. If they just seem curious, again let them get as close as about a foot from you. If they don't really care at all and go about their business, you can hop up on the bed and start playing with the rats. As soon as one or both cats seem a little too interested in the rats, put your babies back in their cage. Remember though, this is once your rats are larger, calmer adolescents! Wait until they are AT LEAST eight or nine months old to attempt this. And even then, you must be VERY cautious.
Cats and rats CAN be friendly, but it can take a long time for any cat (especially adult cats) to transition from predator to playmate. For the time being, don't try it. In the future, IF you decide to try introducing them, BE CAREFUL.
Good luck, and best wishes!