You can get it here http://te4.org/games/addons/tome/steamshaper or on the Steam Workshop.
This subclass has zero new talents but combines basically all of the non-weapon-dependent talents from all three Tinkers (and access to Mindstar Mastery for good measure) into a Willpower/Cunning focused Steam/Psi caster.
Is it viable? I'm not really sure yet , but I wanted to test it and not have my save invalidated, so here it is.
They have a life rating of zero and start with +5 Cunning and +4 Willpower. This class will be locked if you have not unlocked Psyshot."Powerful psionics are able to enter a gestalt with steam generators and technology to enhance their own mental prowess.",
"The Steamshaper combines this ability to gestalt to enhance his tinkers, all the while boiling her foes to death with steamy, mind-induced mayhem."
["steamtech/avoidance"]={true, 0.3},
["steamtech/chemistry"]={true, 0.3},
["steamtech/physics"]={true, 0.3},
["steamtech/blacksmith"]={false, 0.1},
["wild-gift/mindstar-mastery"]={false, 0.3},
["steamtech/engineering"]={true, 0.2},
["cunning/survival"]={false, 0.3},
["technique/combat-training"]={true, 0.1},
["psionic/gestalt"]={true, 0.3},
["steamtech/thoughts-of-iron"]={true, 0.3},
["psionic/action-at-a-distance"]={true, 0.3},
["psionic/psionic-fog"]={true, 0.3},
["steamtech/automation"]={false, 0.3},
["steamtech/furnace"]={false, 0.3},
["steamtech/battle-machinery"]={true, 0.3},
Enjoy!