Currently our build scripts adopt a file-based way to reference our checkstyle configuration. With having lots of sub-modules with a deeply nested structure, this introduces quite some maintenance effort (e.g. when you try to add integration tests).
There is another way to incorporate checkstyles for a project easily: serve them in an own maven artifact and include them as dependency of the maven-checkstyle-plugin.
See OpenWebBeans and MyFaces of how this looks like:
https://svn.apache.org/repos/asf/openwebbeans/build-tools/trunk/ for the openwebbeans-checkstyle-rules, and
https://svn.apache.org/repos/asf/openwebbeans/trunk/pom.xml for how it's being used (see maven-checkstyle-plugin section)
This can e.g. also be used to detect missing ASF headers in java files, etc.