I think he is doing what i was contemplating to do, just use /assist /cast spell to do general pew-pewing but when you're ready to kill a target go with a /cast [target=focus] button and then you can basically launch a couple of volleys before they can react.

So i'm assuming (damn i hate to assume but..)

He's just got lots of buttons with

/assist
/cast spell

and then a few special buttons with

/cast [target=focus] spell


amiright?