Gnome, Goblin and Mechagnome hunters automatically know how to tame Mechanicals. Hunters of other races must acquire the skill from a Mecha-Bond Imprint Matrix, crafted by Engineers who have at least 1 skill point in Legion Engineering.
Located in Elwynn Forest. Tekton is found in a flock of sheep by a house on a high ridge, in the north-east of corner of the river valley that is east of Stormwind. Be very sure to tame him before he can reach you or he explodes!