Unable to change maven.scm.provider.cvs.implementation from Maven POM/Settings

I did not find any way to set the system variable used by SCM internally like maven.scm.provider.cvs.implementation
the only way is to add this to the command line
-Dmaven.scm.provider.cvs.implementation=cvs_native which is error prone and awkward

it should be possible to configure it in the POM and even through activated profiles...

many other system properties may be usefull too.

note that by the way setting maven.scm.provider.cvs.implementation to empty content
should be accepted as "default behavior". it is needed if the property is always configured in a systemProperties element in configuration in plugin element, but with a value which is either empty or not depending on the OS.

Ive tested, without success, simply adding POM or profile properties, or using "systemProperties" element in "configuration" for plugin
like that :

<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-scm-plugin</artifactId>
<configuration>
<goals>install</goals>
<!-- semble pas marcher -->
<systemProperties>
<property>
<name>maven.scm.provider.cvs.implementation</name>
<value>${maven.scm.provider.cvs.implementation}</value>
</property>
</systemProperties>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-release-plugin</artifactId>
<!-- la version 2.0-beta-4 a un bug grave qui empêche de fonctionner si tous les paramètres ne sont pas saisis dans le tag SCM -->
<version>2.0-beta-5-SNAPSHOT</version>
<configuration>
<generateReleasePoms>true</generateReleasePoms>
<!-- semble pas marcher -->
<systemProperties>
<property>
<name>maven.scm.provider.cvs.implementation</name>
<value>
${maven.scm.provider.cvs.implementation}
</value>
</property>
</systemProperties>
</configuration>
</plugin>

<profiles>
<profile>
<activation>
<os>
<family>Windows</family>
</os>
</activation>
<properties>
<!-- sous windows il faut utiliser cvsnt natif... l'implémentation java marche pas -->
<maven.scm.provider.cvs.implementation>
cvs_native
</maven.scm.provider.cvs.implementation>
</properties>
</profile>
</profiles>

thanks in advance