Fill a 5 gallon bucket to the half-way point with shredded paper. If you do not have shredded paper, you can use 4 rolls of toilet paper, including the rolls.
Pour warm water into the bucket until the water reaches the halfway point of the bucket. Let the water and paper stand until all of the paper is very soft.
Use a drill with a paint stirring attachment to mix the paper and water into a slurry with a yogurt-like consistency. Add more water if you need to.
Add small chunks of clay, a few ounces at a time, and mix with the drill until the clay is completely mixed. You are looking for a consistency a little thinner than regular clay. Add and mix more clay until you have the right consistency.
Pour the clay out of the bucket and on to a table. The clay will dry out slightly, which is why it is a little wetter than regular clay. Reserve the amount of clay you need to repair the crack in your sculpture and store the rest as you would store regular clay.
Smooth the paper clay over the crack in your sculpture and fire. Paper clay generally fired to a cone 6. You can also let the clay air dry on larger sculptures and coat with a painted finish that will mimic your sculpture's finish.