With Keyclone, every key you press is broadcast to every window.
That's the default behavior.

You can blacklist certain keys to never broadcast, meaning they only affect the active window.



The easiest follow/assist is going to be focus based.

Every character on the team is going to need one focus macro, per character on the team.
If you have two toons, they both have two focus macros.
If you have five toons, they each have five focus macros.

The macro for Toon A, is on the same keybind for every window.
/focus [target=ToonA]

The macro for Toon B, is the same keybind for every window.
They all have the same macro: /focus [target=ToonB]

Keyclone has a 'Maximizer' which is your window layout.
It helps to set the active region keybind (in Keyclone) to the same keybind as Warcraft sets the focus for the team.
So when you push the key combination to bring Region A to the front/active position, every character sets Toon A as their focus.



Follow is the same on every character.
/follow [target=focus]



Assist is good for classes with auto shoot or auto attacks.
Straight casters can cast at the focus target.

/assist [target=focus]
/cast [target=focustarget] SomeSpellHere

They are effectively the same.
Except that target changes with assist, while it doesn't change while casting at the focus's target.



Keyclone can Round-Robin, where it sends the same input successively to one window after the other.



It also has a mouse broadcast option, which wasn't all that impressive.
If you need to broadcast the mouse, you're better off manually switching to that Maximizer Region, and manually using the ability there.

I ended up switching to IS Boxer, mainly for the improved mouse broadcasting.
But there was a lot more features that blew me away.

Still, you've already paid the $20 for KC.
$20 once, for a lifetime and transferable license isn't that prohibitive.



Basically match abilities with similar cast or re-use times, or put macro castsequences on similar keys.
If both classes have a longer refresh, but instant use ability, you could put them on the same keybind; this is of course easier with classes that are the same, so have the same abilities.
You could go with a Burst Macro, a Standard DPS Macro, an AoE Macro, and a Panic Macro.
Have each on the same keybind, so they both receive the normal DPS Macro, and because the inactive/slave window is macro'd to attack the focus target, and the active window is everyone's focus, they're attacking the same thing.