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.
Flying constructs of the Kyrian of Bastion.
Unconfirmed Looks :
We don't yet know if these looks are available on tameable creatures.