You can go with Vuhdo or Healbot or Grid + Grid Custom Layouts + Clique...
If you want to heal with addons.
Alphabetical sort (or any fixed order, that is the same across all windows).
With a Repeater Region across the zone, block local clicks and sending clicks to your healer's slot or an ATG with your healers in it.

You can use Click Bars instead, over any fixed order sort.
Whether Pitbull, Shadowed Unit Frames, Grid, whatever.
http://isboxer.com/forum/viewtopic.php?f=4&t=2911