Healing using mouse over unit party/raid frames

How does one heal by simply holding the cursor over a character's unit box in a raid frame? Is this possible? I know I am doing something wrong for sure. I have grid installed, but I have to click on the person in raid, move mouse away from the raid box and other players, then cast the healing spell (those are bound, no left-clicking there). Seems terribly inefficient; surprised I'm not involved in more wipes really. I thought the mouse over macros would work, but apparently not for raid frames. Any suggestions or info on this?

You can download Clique so you can assign click casting to your unit frames.

Or you can use a mouse over macro: /cast [target=mouseover, help][target=player]Holy Light , for example.

You know, I've had Clique installed for some time, but have never used it actually. Well now that I read up on it and set it up, this is frigg'n awesome! It should work like this out of the box (WoW healing that is).

Thanks for the direction there Fopp!

How to without an addon:

Macro the spells you want to use with mouseover like this...

Druid:

/cast [target=mouseover] Cure Poison
/cast [target=mouseover] Remove Curse
/cast [target=mouseover] Rejuvenation