m2e: Generated code with exec-maven-plugin

I have been using m2eclipse for 2 years or so and have now switched to m2e.

Unfortunately, this has broken some functionality for me.

In many projects, I have generated Java code, usually generated through a main class in a library project. Here's a typical setup:

<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>exec-maven-plugin</artifactId>
    <executions>
        <execution>
            <id>generateDTOs</id>
            <phase>generate-sources</phase>
            <goals>
                <goal>java</goal>
            </goals>
            <configuration>
                <classpathScope>test</classpathScope>
                <mainClass>com.somecompany.SomeCodeGenerator</mainClass>
                <arguments>
                    <argument>${project.build.directory}/generated-sources/foo</argument>
                    <argument>${project.basedir}/path/to/a/config/file</argument>
                    <argument>more arguments</argument>
                </arguments>
            </configuration>
        </execution>
    </executions>
</plugin>
<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>build-helper-maven-plugin</artifactId>
    <executions>
        <execution>
            <id>addDtoSourceFolder</id>
            <goals>
                <goal>add-source</goal>
            </goals>
            <phase>process-sources</phase>
            <configuration>
                <sources>
                    <source>${project.build.directory}/generated-sources/foo</source>
                </sources>
            </configuration>
        </execution>
    </executions>
</plugin>

Previously, I would just have to import that project with eclipse as a maven project, the code would automatically be executed and the source folder added to the eclipse project.

Now, m2e has installed a "connector" for the buildhelper plugin, so the source folder is created, but I have to manually trigger code generation by executing Run As > Maven > generate-sources. This is really annoying, I would like the maven build to respond to pom.xml changes, Project > Clean ..., SVN Updates, Eclipse startup etc. as it previously did.

What can I do to make m2e work like m2eclipse?