Did you happen to watch the putt I lucked in from 206 feet (almost 70 yards) on the 18th green at Whistling Straits, while filming a segment for The Golf Channel at the 2004 PGA Championship? I'm told it is the longest televised putt ever holed on a green (if you know of a longer one, please write to firstname.lastname@example.org). Pure luck it was, and I know I couldn't make it again in maybe a million tries. I could never read the break of such a putt precisely, and I don't practice enough on putts that long to have a good feel. But I did hit it solidly, and if it hadn't gone in, it would have stopped close to the hole and I could have two-putted, which I'll take every time!
That's my point: The most important thing about long putts is to avoid three-putting. You'll improve your scores more by learning to three-putt less frequently than by learning to one-putt more often.
In testing putts longer than 80 feet, I have discovered that most golfers putt better when they use a long, smooth chipping swing with their putter, which is what I did to hole that 206-foot monster. We teach this technique in our schools, and call it chip-putting. It requires standing taller over the ball, hinging your wrists slightly on the backswing, (1) adding a little body rotation through impact (2) and a long follow-through (3). It's chipping with a putter.
Before you try this on the course, find the longest putt you can and practice this technique. By chip-putting, I think you'll hit the putt more solidly than if you try to make a super-long putting stroke. Your distance control will be better and you'll minimize your three-putts. And maybe, every once in a while, you'll get lucky enough to roll one home.
For information on Dave Pelz, his three-day Scoring Game Schools, one-day Clinics and products, go to pelzgolf.com or call 888-DAVE-PELZ.