You could create a warcraft macro.
Something to the effect:
/cast [target=focus] Nuke

If you assign a focus ahead of time, then that is what you'll be casting at even if IS Boxer has your toon target the same toon as your tank.

You could quite easily open the IS Boxer Toolkit, and remove the FTL Assist Me, from a hotkey for some toons. So maybe the "2" key no longer auto assists, but still broadcasts "2" to every toon.

A lot of options, depending on what you want.