S.M.
Time out, as in sitting on the steps or in a corner, never worked for our son either. He had some awful tantrums when he was 4. What worked for us was to lock him in his room. The previous owners of our house had turned the doorknobs around on the kids' bedrooms, so they locked from the outside. I know it sounds awful, but he was safe and he couldn't leave, he couldn't follow me around screaming, I didn't have to hold him down in his time-out place (counterproductive!) and it removed him from the situation. I would set a timer to start his 4 minutes (his age!) as soon as he was quiet. Usually, he was asleep by the time it went off, but that was okay, we both needed the break.
Fight and win these battles now while your child is smaller than you. Children need to know there are adults in charge; it makes them feel safe. Be very careful to choose only battles that are important.
It's easier to avoid a tantrum than it is to punish for one. Ward them off when you can. Here are my basic tantrum-avoiding rules:
-Give warnings that it is almost time to leave, or go to bed, or turn off the TV.
-Repeat what your child is saying so they know you understand what it is they want. Explain why they can't have it right now.
-Ask for help in little ways when you are doing chores.
-Let your child know ahead of time what you is expected, and what will happen if the rules aren't followed.
-Offer choices whenever you can, even if they seem unimportant to you. (Do you want to make your bed before or after breakfast? Do you want to put away the blocks or the train first? Do you want apples or carrots for your snack? Which shoe do you want to put on first?)It will give a sense of control over the world, which is what a lot of tantrums are about.
-Recognize good behavior and reward it with your attention. Read an extra story at night if it's been a good day.
Our son is 20 now, and gave us some clashes of will as a teenager too. Although we had some tough times, these stubborn streaks turned out to be the hallmark of a very persistent, independent young man.
Hang in there, and good luck!