embedded gradle shrinkwrap-resolver - propagate project properties via API

I'd like to propagate project properties to embedded gradle build.

I tried following:

 ShrinkWrap.create(EmbeddedGradleImporter.class)
        .forThisProjectDirectory().forTasks("build").withArguments("-x", "test", "-Psomepropname=somepropvalue")
        .importBuildOutput().as(WebArchive.class)

but the somepropname is not set in embedded build.

Using the gradle.properties is not an option for me, as somepropname value changes from build to build.

Workaround was to write temp properties file and read it in embedded build with silent failure (as suggested here: http://issues.gradle.org/browse/GRADLE-1419?focusedCommentId=16245&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-16245) but that sounds too much work to do for such a simple task.