How to compile multiple css files into individual swfs using pure Maven?

Question

Right now I am using an apply task inside of an antrun execution.

<plugin>
    <artifactId>maven-antrun-plugin</artifactId>
    <version>1.4</version>
    <executions>
        <execution>
            <id>compile-default-theme-css</id>
            <phase>compile</phase>
            <configuration>
                <tasks>
                    <apply executable="${mxmlc.path}" dir="${basedir}/cssdir/">
                        <srcfile/>
                        <fileset dir="${basedir}/cssdir/" includes="*.css"/>
                    </apply>
                </tasks>
            </configuration>
            <goals>
                <goal>run</goal>
            </goals>
        </execution>
    </executions>
</plugin>

How do I do this in pure maven? Without the antrun plugin?