Doesn't seem to do anything. The command can't be entered while hildon-desktop is running, and shutting down it first brings us back to original problem (Qt apps won't survive the hildon-home restart if they are running). Even after I've shut down the hildon-home with dsmetool and then bring it back to life with -theme argument, nothing is changed. I've tried to offer it these:
-theme name_of_the_theme
-theme /path/to/the/theme