I haven't been on my mage in a while but my setup should still work with good dps. I use the default Blizzard macros, Bartender4 addon, and /click castsequences. I can't remember the exact layout off hand, but next time I log in, I'll post here what it is.

If I'm not mistaken, the Arcane Missile procs are woven into the sequence so you don't have to worry about watching for them and they fire off about 95% of the time they are up, it's really dependent on lag and how often you press the keys I guess.