Soooooo...
This is the easiest way I see to access any MV plugin in MZ. In a Script command:
this.command356(["pluginCommand parameter parameter etc"])
Please notice the square brackets.
But trying this with my plugin doesn't quite work due to a minor difference between how the sound files are accessed between MV and MZ, unless you add a forward slash - / - to the beginning of the file name. Yyyup. That is arbitrary. But it's also the only way it works. (If you're using aliasing, you only need to include the forward slash in the Load command.)
In theory, I could make an MZ version of the plugin, but I haven't done much MZ stuff and don't currently know how to register the commands. I'm sure I could learn, I'd just need to get around to it...