Since we do not want to include usernames and passwords in clear text in a project xml file, you should probably use the maven settings.xml for this.
https://maven.apache.org/settings.html

You can then use the properties-maven-plugin within the fcrepo-jms-indexer-webapp/pom.xml:
http://mojo.codehaus.org/properties-maven-plugin/plugin-info.html

such as:
<code>
      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>properties-maven-plugin</artifactId>
        <version>1.0-alpha-2</version>
        <executions>
          <execution>
            <goals>
              <goal>set-system-properties</goal>
            </goals>
            <configuration>
              <properties>
                <property>
                  <name>fedora.repo.username</name>
                  <value>${fedora.repo.username.from.settings}</value>
                </property>
                <property>
                  <name>fedora.repo.password</name>
                  <value>${fedora.repo.password.from.settings}</value>
                </property>
              </properties>
            </configuration>
          </execution>
        </executions>
      </plugin>
</code>