Is there any way to keep the brotherhood of steel alive WITHOUT working for the smiley face of DEATH.

Do all of the quests for McNamara, ignore Hardin, work for the NCR.

Above

Those are the only 2 ways to keep the BOS alive.

Hmm...
I finished the game only once, doing the Yes-Man way. In this game the BoS made peace and allied with the NCR.
I told Yes-Man to ignore the BoS.

When I met General Oliver I just talked him down to leave in peace.

Until now I thougt, the BoS will be save this way. Did I kill them?

work for NCR and have them team up with brotherhood, if you did this, you can then put on BOS armor and NCR won't attack you