As I understand it you can receive power armour training in one of two ways.
First, help the Brotherhood of Steel and gain their trust so they train you to use it.
Second, acquire Arcade Gannon as a companion and follow his personal quest line.
Is that it?
Problems:
The way I'm role playing this character, he can't help the Brotherhood. He's selfish and impulsive and the Brotherhood has not given him any reason to help them. I'd be breaking RP if I helped them and I do not want to do that. With Veronica as a companion I've encouraged her to leave the Brotherhood, as they've treated us like dirt, including trying to murder us. They also want my eyebot, and since I do not trust them or their intentions, they aren't getting my damn eye bot. Makes no sense to help them especially when no reward has been offered.
As for Arcade Gannon, he will not like my character because I am sided with the legion. I read that you can complete his quest by putting on NCR armour, but that's stupid. First of all I'd have to metagame by putting the NCR armour on, and second of all it doesn't make any sense that Gannon would be fooled by a costume. I'm the same guy underneath it.
So do I just give up on the power armour dream I had for this character?