I have a hunter and shaman in one of my makeups. I use the following macros bound to the same key. The hunter loses a little dps since his cast time is 1.5 and the shaman is 2.0, but not enough to worry about.

Hunter
#showtooltip Steady Shot
/cast [target=focustarget] !Auto shot
/cast [target=pettarget,exists] Kill Command
/cast [target=focustarget] Steady shot
/script UIErrorsFrame:Clear()

Shaman
/cast [target=focustarget] Lightning Bolt