Setting unsaved-value...

Hi,

    I am trying to get Hibernate to generated the unsaved-value="X" on the primary key. 
    Looking at the velocity template it appears that $table.generatorUnsavedValue needs to 
    be set for this to happen. I've tried setting the unsaved value in the prefs.properties file
    but middlegen is not picking it up

    So what is the best way to set unsaved-value so that it is generated in the hbm.xml file ?

Thanks,

Fernand