There are two ways of obtaining this training. Without this perk, any power armor found cannot be equipped.
If you do not ask for training on your own, you will get it automatically at the end of The American Dream when you become an honorary member of Lyons' Pride, however these options appear very late in the game. Once that's done, you may use any kind of power armor, including the Enclave and the Outcast variants. There is no charge or other requirement for training - the screen simply fades to black as Gunny begins teaching you. After gaining permission from Elder Lyons, speak to Paladin Gunny in the A-Ring of the Citadel.Prior to this perk, equipping power armor was impossible. This perk allows one to use any kind of power armor in the game.
