I would like to simplify the way I cast targetable spells in WoW (Blizzard, flamestrike, heroic leap, etc). Right now I'm using a simple @cursor in-game macro to cast wherever the mouse is. But sometimes that isn't precise enough.

I'd like to find a way through some combination of in-game macros, addons, or allowed 3rd party software, such that pressing down a key brings up the targeting reticle, and then releasing that key casts the spell.

In my mind this is a simple key remapping task. I want key down to perform 1 action, and then key up to perform another action.