AdditionalViewEngine.java

/**
 * This will result in an additional ViewEngine. The priority ensures 
 * that this implementation is preferred. 
 */
@Priority(1000)
public class AdditionalViewEngine extends FreemarkerViewEngine {

  @Override
  protected Configuration buildConfiguration() {
    Configuration config = super.buildConfiguration();
    // customize here
    return config;
  }

}

SpecializingViewEngine.java

/**
 * This ViewEngine implementation will replace the existing FreemarkerViewEngine.
 */
@Specializes
public class SpecializingViewEngine extends FreemarkerViewEngine {

  @Override
  protected Configuration buildConfiguration() {
    Configuration config = super.buildConfiguration();
    // customize here
    return config;
  }

}