Big Mig may have been 6'2", but he was also whip thin at 176 pounds and had some crazy respiratory and cardiac anomalies, like an 8L lung capacity and a 50L/min cardiac output. The guy had cycling in his genes.

For the rest of us, the best climbing advice I received was from an ultradistance racer and randonneuring friend of mine. He caught me slacking on a climb during an early season training ride, and as he rode past me he yelled "STAND UP, BIG MAN!"

Standing up works. Use your weight to your advantage: Go one or two gears higher than you'd sit and spin for a given pitch, stand up, shift your weight forward so you're centered over the forward position of the crankarm instead of centered over the cranks for spinning. Stand up on that forward pedal and just let your weight do the work.
You might not go any faster with this technique, but it's not about the speed. It's about playing gravity to your advantage, even when you're going uphill.