Custom Android build.xml for rename manifest package

Question

I wanna build one app into 2 version, one paid, one free, and I know aapt have a option "--rename-manifest-package" should help, but I don't know How to use it in build.xml. I find 2 place I may modify:

 <!-- first -->
 <target name="-resource-src" depends="-dirs">
    <echo>Generating R.java / Manifest.java from the resources...</echo>
    <exec executable="${aapt}" failonerror="true">
        <arg value="package" />
        <arg line="${v.option}" />
        <arg value="-m" />
        <arg value="-J" />
        <arg path="${gen.absolute.dir}" />
        <arg value="-M" />
        <arg path="AndroidManifest.xml" />
        <arg value="-S" />
        <arg path="${resource.absolute.dir}" />
        <arg value="-I" />
        <arg path="${android.jar}" />       
    </exec>
</target>



 <!-- sencod -->
 <target name="-package-resources">
    <echo>Packaging resources</echo>
     <aaptexec executable="${aapt}"
            command="package"
            manifest="AndroidManifest.xml"
            resources="${resource.absolute.dir}"
            assets="${asset.absolute.dir}"
            androidjar="${android.jar}"
            outfolder="${out.absolute.dir}"
    basename="${ant.project.name}" >
</aaptexec>
</target>

this article( http://blog.uncommons.org/2010/07/19/building-two-versions-of-the-same-android-app/ ) said I should adding "--rename-manifest-package" at the second place, but How?