There is a moving iceberg that transports you to the cheese and back. Since this iceberg is quite slow, you have 5-6 seconds to get on the iceberg before it moves away and takes the other mice who got on all the way to the cheese. Do not push the iceberg too fast, or it will go faster than the mice on it, letting them slip and fall, including you who pushed it.
Get on the iceberg with the other mice and take them to the cheese, and you and the iceberg lead them back. Mice who haven't got on yet can get on when the first group of mice have come back for the hole. Do not attach runes to the ice block, as this will have the ice block move faster than the mice can. So the mice fall off the block and die.