In Vectorworks 2018 menu commands can now be created with Marionette. To create a menu command, right-click on a wrapper and select Convert to Menu Command, and give the menu command a name exactly as you would like it to appear in the menu. After it is created, it will be available under Tools > Marionette Commands > [Command Name].
This command works as a simple find and replace command for class names. It makes use of a User Interaction node which allows you to enter text while the command is running. Once you run the command, in the first dialog box that pops up, enter the text of class names that you want to replace. In the second dialog box, enter the text that you want to replace it with. If there is more than one instance of the text in the class name, it will only replace the first instance. To change more than one instance, simply run the command again. If you make an error, you can simply use the Undo command.