A minion created with Minion of Chaos is able to select Psyker as one of the traits, however Psy Rating (which is needed to pick up any powers, relevant talents and so on which got anything to do with psykers) is a tier 3 talent, which means you're not able to get it.
As far as I know you don't get Psy Rating 1 automatically when you get the Psyker trait. Why is the trait even there, if so? Kinda hard to make a wyrd sorcerer with Minion of Chaos (which it implies you're able to create, according to the talent description).