I'd recommend taking a look at mouse based (repeater regions) healing.

IS Boxer has a feature, where broadcasting turns on when the mouse is inside the region.
And turns off when the mouse leaves the area.

Basically, you get Grid/OpenRDX/Healbot/Vuhdo and have a frame for each member of the team.
You have it sorted alphabetically.
And then click on the frame you want to receive a heal.
Healbot/Vuhdo are all in one, or Grid/OpenRDX will require something like Clique to interpret the clicks.
You can include modifier keys with your clicks, giving you a ton of options.

HKN can also be used, for mouse broadcasting scripts.
I haven't used HKN this way, but know others have.
HKN is free, which is a good price.
IS Boxer is $10 per 3 months or $36 per year.