In C, all Rational Statemate elements can be incorporated into a callback routine. Normally, if you are using elements in callbacks, it is not necessary to create hooks. However, for states, you need to tell Rational Statemate in advance which states are going to be used in a callback, so an appropriate ID can be generated.
For more information on how to use callback routines in the user code to track model changes, refer to Callbacks for Compound Elements.