I'm not sure I understand your question.

Each wow instance is its own instance irregardless of which computer it's on or if you are multiboxing. So the in-game macros have basically the same visibility to the rest of the world, your other characters, etc.

Again, not really sure what you're asking, but I haven't found anything yet that I can't do while software multiboxing that I'd be able to do with hardware and multiple computers, from a macro-ing perspective anyway.