Well you can rebind whatever you're using for renew because disc priests don't need it.

My disc priest click heals are the following:

shift left : shield
ctrl left : prayer of mending
alt left : pain suppression
alt right : void shift (almost never use it)
shift right : greater heal
mousewheel click : flash heal
mousewheel up : dispel (I rebind my camera to ctrl mousewheel, life is much better if you aren't changing your camera accidentally all the time!)
alt mousewheel click : penance (but I usually cast penance as part of my atonement spam)

I have my aoe healing button (inner focus + @mouseover Prayer of Healing) bound to a spamming G-key key next to my normal dps key, and for dps and tank toons that key in isboxer just calls their normal dps rotation.