They fixed the bug, do not use...
/cast !Auto shot
/cast [target=pettarget, exists] Kill command
/cast Steady shot
...anymore! The Auto shot would only be fired when Steady shot was just fired, but the global cooldown to start the next one is not ready yet.
You will get very low dps with this now.
Use...
/cast [target=pettarget, exists] Kill command
/castsequence !Auto shot, Steady shot
...instead.
If you get a very slow weapon (3.1 or higher) you can use
/cast [target=pettarget, exists] Kill command
/castsequence !Auto shot, Steady shot, !Auto shot, Steady shot, !Auto shot, Steady shot, Arcane Shot
But there is a problem. Since Auto shot will be fired when no cast is happening it can happen that you will get one auto just before the arcane. This is a problem since the rotation will halt till the next autoshot now.
Thus: Including Arcane shot into rotations can mean a loss in dps if the damage.
You can see it on this graphic for a BM hunter:
BM macro with 2.7spd bow
I tried it with my 2.7 bow with 1.96 speed. Normally there should be enough room to do one steady and arcane while auto shot is on cooldown, but something seems to slow things down and the Auto Shot timer is ready before I can fire my Arcane shot. Hmm.
When will the global cooldown from steady shot start? When it fires? This would explain it.