Put the babies in this area and wrap the blanket all around them. Leave an air pocket so the kits will have some air to breathe. Keeping checking on the rabbit kits to make sure they don't get too hot. Once they are revived either return them to their mother's care or foster transplant them to the care of other rabbits that will take care of them. Another way I have used to warm up rabbit kits suffering from hypothermia is through the use of a hair dryer.
Hair dryers make great ways of warming up chilled baby rabbit kits.
I have seen seemingly dead rabbit kits come back to life after using a hair dryer on them. First thing you want to have on hand is a pretty good size bowl that you use for nothing but warming rabbit kits. Line this bowl with some hay and put the chilled rabbit kits in it. Next use the warmth of a hair dryer blowing on the kits to bring them back to life if it's possible. Always keep your hand near the rabbit kits to make sure they are not getting too hot.