Here is a xsl file for initial support of embunit xml output.
Also note that the usage of putting xsl's in dirs like: /var/lib/jenkins/userContent/xunit/embUnit/1.0.0/
As mentioned in docs seem non working. I never was able to get it to show up in selection box, nor able to put some relative path in the custom xsl dialog box. On older xunit's full paths seemed to work fine, but on current it seemed to require the xsl to be in the working directory.