Design pattern for replacing a class used in a library with another one

Is there a neat way to replace a class X with a better class Y without going through source code to replace them manually?

Concrete Example: I am working with with the ECJ library for evolutionary computing. This library has a good implementation of random number generators that the library uses extensively. I need to use this library for solving some routing problems. These problems are implemented into a library that utilises Apache Commons Math and hence uses the RandomDataGenerator class extensively. When tailoring the two libraries together, using different random number generators leads to some undesired behaviour and it is better to use the generators ECJ provides. Is there a way for me to refactor the routing library to use replace RandomDataGenerator without going through the large code base and doing it manually?