The CONFIG module should be producing a JAR with the filtered resources in its root. The other modules should be able to access those resources via their classpaths, which should contain the CONFIG jar, using ClassLoader.getResource(String) or ClassLoader.getResourceAsStream(String).
EDIT: after comment below.
You don't need to re-declare the Resources plugin, you simple specify the resources in the build section of the pom like this:
<build>
<resources>
<resource>
<filtering>true</filtering>
<directory>src/main/resources</directory>
<includes>
<include>**/context*.xml</include>
</includes>
</resource>
</resources>
</build>