Looking at what Khatovar tested, I tried a few other things (didn't know about the 0,0 macros), and came up with this.
Code:
/stopmacro [channeling]
/castsequence Shadow Word: Pain,Vampiric Touch,Mind Blast, 0, 0
/cast Mind Flay
/cast Devouring Plague
/cast Mindbender
Went with a different level 3 talent (Mindbender) which does fire off pretty much on cooldown. Got a bit of a dps gain. All the failthru spells due trigger.
Need to go and try it in a LFR run, and see how real-world performance is.
I don't think it's going to be possible to use the SW:I talent, I can't find a way to get the macro to proc it at the right time. Even adding the extra 0,0 times it out right, but it still doesn't trigger. If I put SW:I in front of some of the other talents, it will hang on that until it can be cast.
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