Well, if you make a Keymap with a hotkey of choice.
It sends the hotkey to each wow client.
Target can be every pally client.

Then within warcraft create macro's.
Put them on the same keybind as the hotkey.
Each pally will have:

#show Hand of Freedom
/cast [target=Next Pally] Hand of Freedom



Not really sure how to make it work with ISBoxer - wow macro actions.
Have not had much success (read haven't played with them much) yet.
But with the keystroke type action and a wow macro, pretty easy to get your desired result.