The idea behind the Poison Monk is based off of the procs of Andariel's Visage; Mad Monarch Scepter; Hexing Pants of Mr. Yan and Tempest Rush.
(The Hexing Pants of Mr. Yan is for the increased damage and resource regeneration while you're moving.)
I have done quite a lot of testing with this build and it seems as though the proc on the Andariel's Visage mixed with the proc of killing 10 enemies with the Mad Monarch Scepter is just enough to be able to clear quite fast even through Master difficulty. I haven't tested it in Torment difficulty yet, that testing will come later today.
I don't want to see you pour your time into something that won't be effective past t1. We have no poison runed abilities .therefor all poison elemental dmg would be useless to use. If you are wanting to tempest rush it's only viable in firebuilds right now. Lastly I've tried it lol there is just no synergy to be had when we have no poison abilities.
It's certain items. Shard of hate's proc scales with + elemental, as does Odyn son. I *think* you can tell by the wording on the unique affix; SoH has it's 'ability' starting with a capital letter, as if it's an actual skill. Same with Odyn son, it reads Chain Lightning, so it will actually scale. Poison Nova seems to work the same.
So actually a monk with all +psn damage and say Shard of Hate + Mad Monarchs could work. Probably not near as well on the highest of torments, but I could see it working on T1. But the OP might want to use another skill that will proc SoH more, such as a generator.