Maybe something like this?
Code:
/castsequence reset=combat/30 [@pet] Misdirection, Arcane Shot, Mend Pet, Arcane Shot, Arcane Shot, Arcane Shot, Arcane Shot, Arcane Shot, Arcane Shot, Arcane Shot, Mend Pet, Arcane Shot, Arcane Shot, Arcane Shot, Arcane Shot, Arcane Shot, Arcane Shot, Arcane Shot, Mend Pet, Arcane Shot, Arcane Shot, Arcane Shot
I have stopped playing so unable to verify. I though think a simple cast with a modifier may be easier since the purpose seems to be to control different abilities in a single keybind.
Code:
/cast [mod:shift, @pet] Misdirection; [mod:ctrl] Mend Pet; Arcane Shot