As for HKN, and using this technique the reliability is realy good.
I personaly use such a technique for all of my group healing and cc-spells.

As how to implement this on HKN, there are two different ways:

1. You could, when in the specific area of the panel, broadcast the mouseclick to the specific window.
2. You could, when in the specific area of the panel, broadcast a key to a specific qindow, which is bound to the action you want to use (this is the one i'm using).

- If you wan't further instructions, how to do this with HKN simply say so (or may be read this thread)