You'd put in a new macro in a macro set that your character set uses and give it a unique keybind, yes. Then you can call it up in a mapped key with a Named World of Warcraft Macro Action. The reason the keybind is required (and needs to be unique) is that ISBoxer will create the macro in the addon and give it that same keybind ingame to have it accessible. So you'll not actually be sending the macro itself, but that bind instead, which triggers the macro ingame.


Bit of a TL;DR explanation, but that is the general idea.