A custom Checker configuration xml file can be defined and then referenced via a URL, File, or build classpath resource reference.
To reference a custom Checkstyle Checker configuration, use the configLocation parameter.
<project>
  ...
  <reporting>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-checkstyle-plugin</artifactId>
        <version>2.4</version>
        <configuration>
          <configLocation>checkstyle.xml</configLocation>
        </configuration>
      </plugin>
    </plugins>
  </reporting>
  ...
</project>
This example causes the Checkstyle Plugin to check for a File named checkstyle.xml or a resource named checkstyle.xml within the compile scope of the dependencies or build extensions classpath.
There are 4 predefined Checkstyle configuration definitions that ship with the Checkstyle Plugin, the Sun Microsystems Definition is selected by default.