That is a tough one,
You can try "baiting" the snake out with some food, and perhaps setting up a area with a heat lamp and a hide with the rat, close to the opening.
With any luck he may come out to eat and warm up.
Another option may be to get some kind of broom handle and push it out. Other than that you may have to cut some of the material away.
Associated Serpents Inc.
The Green Mile-Rodent Feeders
Before you criticize someone, you should walk a mile in their shoes.
That way, when you criticize them you're a mile away and you have their shoes.