My guide gives a good overview of boxing with IS Boxer.

Essentially Keyclone broadcasts everything always.
IS Boxer will only broadcast everything, if you turn repeater on.

With Keyclone, you can white list (only broadcast these keys) or blacklist (never broadcast these keys).

With IS Boxer, you can white/black list, but this is much weaker then Keymaps.
Each Keymap has a hotkey to activate, targets one or more windows, and outputs an action to the targets.
An action can be a keybind for a wow macro, it can be a macro created within IS Boxer, it can enable/toggle/disable another keymap etc...

You can make a Keymap for whatever you want.
It seems like a bit of a hassle to begin with, but a Keymap is amazingly powerful in what it can do.

I give a lot of examples, which are basically to the effect of:
Copy how this existing Keymap (made by the wizard) works, but apply it to our new Keymap to do whatever.