You create a new project. The new project is your EAR assembly project which contains your two dependencies for your EJB project and your WAR project.

So you actually have three maven projects here. One EJB. One WAR. One EAR that pulls the two parts together and creates the ear.

Deployment descriptors can be generated by maven, or placed inside the resources directory in the EAR project structure.

The maven-ear-plugin is what you use to configure it, and the documentation is good, but not quite clear if you're still figuring out how maven works in general.

So as an example you might do something like this:

<?xml version="1.0" encoding="utf-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.mycompany</groupId>
  <artifactId>myEar</artifactId>
  <packaging>ear</packaging>
  <name>My EAR</name>

  <build>
    <plugins>
      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <configuration>
          <source>1.5</source>
          <target>1.5</target>
          <encoding>UTF-8</encoding>
        </configuration>
      </plugin>
      <plugin>
        <artifactId>maven-ear-plugin</artifactId>
        <configuration>
          <version>1.4</version>
          <modules>
            <webModule>
              <groupId>com.mycompany</groupId>
              <artifactId>myWar</artifactId>
              <bundleFileName>myWarNameInTheEar.war</bundleFileName>
              <contextRoot>/myWarConext</contextRoot>
            </webModule>
            <ejbModule>
              <groupId>com.mycompany</groupId>
              <artifactId>myEjb</artifactId>
              <bundleFileName>myEjbNameInTheEar.jar</bundleFileName>
            </ejbModule>
          </modules>
          <displayName>My Ear Name displayed in the App Server</displayName>
          <!-- If I want maven to generate the application.xml, set this to true -->
          <generateApplicationXml>true</generateApplicationXml>
        </configuration>
      </plugin>
      <plugin>
        <artifactId>maven-resources-plugin</artifactId>
        <version>2.3</version>
        <configuration>
          <encoding>UTF-8</encoding>
        </configuration>
      </plugin>
    </plugins>
    <finalName>myEarName</finalName>
  </build>

  <!-- Define the versions of your ear components here -->
  <dependencies>
    <dependency>
      <groupId>com.mycompany</groupId>
      <artifactId>myWar</artifactId>
      <version>1.0-SNAPSHOT</version>
      <type>war</type>
    </dependency>
    <dependency>
      <groupId>com.mycompany</groupId>
      <artifactId>myEjb</artifactId>
      <version>1.0-SNAPSHOT</version>
      <type>ejb</type>
    </dependency>
  </dependencies>
</project>