Yes. The easiest way to do this is meet the BoS, find the three patrols, install Hardn's as elder (His questline is a MUCH shorter questline than McNamaras. Since you dont need the BoS, it's best just do Hardin to be done with the BoS), do Hardins task, report back, obtain PA training from Hardin, and either immediately or wait until Houses questline to destroy the bunker.
I do it in every playthrough, it's very easy
Hardin's quest has you kill the Van Graffs though, which closes off the big energy weapon merchant in the game.
Also, even if you kill the Brotherhood, there's still another option to get PA training. Do Arcade Gannon's quest.
Unfortunately, I didn't know the Scorched Sierra Armor needed Power Armor Training (Well, by the time I got the add on the BOS was dead and I was Idolized by CL) and there was no way I could get Arcade Gannon to even follow me, so there was no way I could wear it... However, you can always go that route instead of the BOS, its a faster option depending on how fast you get his quest.
Huh. Have you tried wearing NCR faction armor when trying to recruit Arcade?
Also, Arcade's quest needs you to be fairly far along in the MQ while the Brotherhood can be done whenever.