#showtooltip Shadow Dance
/cast [nomod, nostance:3] Shadow Dance
/cast [nomod, stance:1/3] Premeditation
/cast [nomod, stance:1/3] Ambush
/cast [mod:shift] Eviscerate
/script UIErrorsFrame:Clear()
This will cast Dance if available and not already in Dance (stance:3), then Premed, then Spambush. If you hold shift you'll Evis. The last line prevents any error messages. Error sounds I just have turned off via Blizz's Interface config.
You could also put "/cast [nomod, nostealth] Shadowstep" as the "opener" if you like. "stealth" and "stance:1" are the same thing for clarification.
Poisons, if you like addons, I highly recommend
Ara Broker Weapon Buffer, which will give you 3 LDB timers for MH, OH and Thrown.