You can set up a 2-step macro in ISBoxer that effectively does this, but you'll have to press the button once for each action to happen (anything else would be verboten). Round-robin macros are simply multi-step macros that target a different character for each step. Think of it that way and you should be able to easily make the steps.

There are already threads on here that explain how to do 2-step macros, and there is already an example _built-in_ to ISBoxer that shows you how to do round-robin. I suggest you start there.