One thing that has worked for DS4, my OE tantrum-y kid, now that he's 4 and able to use his words more effectively is to train him in that direction.
My big secret weapon is to ask him to rate his feelings on a scale from 1-5, where 1 is "fine" and 5 is "Oh! Woe! I will die of a shattered heart any moment now!" (Laying it on thick helps, I think, so that he understood that 5s are rare to nonexistent. Our cat had died not long before I started trying this, and so I used that as about a 4...)
Then ask him to rate the significance of the actual triggering event on the same scale, taking into account harm done, reversibility/ease of correcting the problem, duration, and so on. Losing an arm is a 5, a wrinkled sock is a 1.
Then I ask him to compare his response to the event itself and decide if his response is merited.
This approach does 2 things (at least!): 1) it tosses him right out of *feeling everything SOOOOO deeply* mode and into analysis and thought, and 2) it allows him to see for himself what the rest of the world sees--the disconnect between the trigger and his emotion.
Before I tried this with my 4yo, he threw a fit over his shoes and socks every single bloomin' day! It was maddening! Tears, screaming, and my patience was at an end!
Within a week of doing this 1-5 trick, he had stopped crying over his shoes and socks entirely. It was like magic! He even smiled and asked for help when something was bothering him. The angels sang, it was so miraculous!!!
My only regret is that I didn't start doing this sooner. He's so much more self-controlled.
And as a final thought, my kids both melt down when hungry or tired. During a growth spurt, they get hungry a lot more often than I expect them to. I find that tantrums are greatly minimized by keeping blood sugar up. I have read on another GT forum--with no evidence whatsoever to back this up, so it may be hooey!--that GT kids tend to be more sensitive to low blood sugar, and that brain work makes people hungrier than exercise. If any of that is true, then the answer may be as simple as a healthy snack containing some protein and whole grains before a meltdown...
Feel free to ignore, but that's the stuff that comes to mind!