I would approach it the way NY Biker does, except I might be in my 3d lowest or 2nd lowest cog, to give me some "escape" down to the very lowest. It might be just the perception in my mind, but, if I know I have at least one more gear, it helps. And, steady, even round circles on the pedals, as I settle into a steady cadence, even at a low speed. While I don't have issues with my lungs while climbing, I usually climb these types of grades as slowly as I can... especially if they are in the middle of a long hard ride.