I assume you are aware that Maxwell Scatter is already implemented in the plugin, so I am not sure what you are asking (specifically, not sure what you mean by saying "multiple").
Oh, I see, you mean you want a way to use more than one Maxwell Scatter on a given entity. I'm not sure what it would take to do that, but I can put it on my list. The way of doing it now, would be to duplicate the entity, move it down a couple of millimeters, and scatter a different MXS on it.
It's not a limitation of the Maxwell Scatter extension itself, which is a modifier (an object can be assigned multiple modifiers), but rather of the plugin, where it's non-trivial to extend the UI to support multiple modifiers per entity.