There is an easy way I use that might work.

Try something like this script:

<Hotkey LButton>
<PassThrough>
<If MouseIsOverWindowRect Wow1 517 299 30 30>
<SendLabel Healer>
<Key F1>

<Else If MouseIsOverWindowRect Wow1 548 299 30 30>
<SendLabel Healer>
<Key F2>

Key F1 is bound to macro that heals Shaman and Key F2 is bound to a macro that heals the Warlock. You click on that rectangle and book, the healer macro kicks off instantly (use /stopcasting obviously). No lag as it sends a keysrtoke straight to the Healer's screen. It uses extra keybindings, but hey, we got a ton of them. Now, just change the coordinates that I have to be where your Toon's Icon is and when you left click on him, he gets healed.