Have you done much healing? What is your approach, and how effectively do you want to safeguard all party members? Speaking as a veteran healer and DPS – and occasional tank – I wouldn't want you healing ANY group I was in if you were coming in with the philosophy of "Hey guys! I wanna see if I can do this (to steal Bavra's image) with one hand tied behind my back." Remember that while you are working out the bugs and "seeing if this works," the party will be wiping, and you will be wasting at least four other people's time. When you explain what you are doing, their fingers are going to be nervously twitching over their kick buttons.
Simply put, you will be a MUCH better healer if you adopt the philosophy of, "My teammates aren't there for ME, I'm there for them."
I played a priest to lvl70 back BC. The guild I was in cleared all of Black Temple, but never finished the Sunwell... So it's been a WHILE since I've done any serious healing.
At level 20 here, things aren't too complicated, when it comes to healing; Flash of Light when you can, Holy Shock to healing while moving, and Word of Glory for emergencies.
The goal is to create a reliable way to heal without using the mouse at all. The aim would be simplicity while maintaining efficiency.
However, playing devil's advocate here: since you're a trial twink on Aerie Peak, it shouldn't be hard to find four other players who'd be okay with you trying it out, especially since the first couple dungeons would be a much safer environment than if you were to attempt this in level 90 heroics. Try it in Deadmines or WC, if it goes well, step it up in the Stockade.
But I agree that subjecting other people to "I wanna see what happens" is rather selfish, and trial twinks have a bad enough rep as it is. It's one thing to have physical limitations, or to be stuck with a laptop and no mouse, but to do it for the sake of doing it, you'll gain a lot more ground when the other people involved are working with you.
Uh-oh, someone is on to me lol. Yea, I'm not gonna jump straight into a group environment without working out the bugs, don't worry.
I've never run outside macros inside WoW, but if you can, then it should be possible.
You can create a macro that sends the mouse pointer to any location on your screen and click or just hover at that location. I imagine this sort of script is frowned upon or blocked though, I'm not really certain. Still, it's just mimicking mouse input, so it shouldn't be too egregious an over stepping of propriety.
Just use a part frame set up you like, macro the proper portrait positions to the keyboard and you should be good to go.
I've been looking at that program for sometime actually, but if I understand what you wrote, I could just use the in-game keybinds, or macros, to select party frames when healing.
I do appreciate the suggestion though; it's creative stuff like your comment that made me think to post here :)