You should use profiles.
<profiles>
<profile>
<id>otherOutputDir</id>
<build>
<directory>yourDirectory</directory>
</build>
</profile>
</profiles>
And start maven with your profile
mvn compile -PotherOutputDir
If you really want to define your directory from the command line you could do something like this (NOT recommended at all) :
<properties>
<buildDirectory>${project.basedir}/target</buildDirectory>
</properties>
<build>
<directory>${buildDirectory}</directory>
</build>
And compile like this :
mvn compile -DbuildDirectory=test
That's because you can't change the target directory by using -Dproject.build.directory