MiRai has an awesome vid here somewhere I'll try and find, but essentially, I use the VideoFX and Repeater region. I make a Video FX on my healer, and put the repeater region on top of that. Then I simply copy it over to the main, and when I need a heal, I click on the person who needs it.

Works with Clique Grid, Vudhu, Healbot, etc. etc.

Otherwise, you could do a macro that is simply

/cast [target=tankname] spell

or even castmacro [target=tankname] spell, spell, spell

I used to do this and have the various heals on my Numpad, Then it was a simple spam of my DPS key (3) and heals off of num pad.

Stephen