When dealing with a steamroller, also known as the verbal "big bully," stay calm. Typically, they are trying to "rile you up," wanting you to elevate your emotions to their level. Don't let them do it. Keep eye contact with them. Remain assertive. Let them go on and on, let them unwind. Then when they spool down a bit, interrupt them!
When you interrupt them, you will have the chance you need to become assertive. That's when you pick up the ball. One effective approach is close to Muhammad Ali's Rope-A-Dope! Muhammad Ali was known to have the ability take a great many punches to his mid-section. He would lean against the ropes, and let his opponent "box himself out"/get tired. He would wait for his opportunity, and then, BAM! He would knock them out. In a similar fashion, you should do the same thing verbally when dealing with the steamroller. Allow them to verbally wear themselves out, and then, when you see your opportunity, BAM! You take your turn.
Call them by name, and then say, "OK, now wait a minute, I have something to say. I've been listening to you, now you listen to me." You will start, and what will happen? They will interrupt! What should you do? Be assertive! Say, "Hey, I said wait a minute. I listened to you, now it's my turn." Don't back down! That's what they expect! Also remember to keep eye contact. Just don't back down. You may not "win" the argument or discussion, but once you stand up to them, they typically will become your best buddy. It only takes one time! They may still bully other people on your team, but they won't bully you any longer. By going "toe to toe" with them, you may have just earned their respect.
From Tim McClintock, PMP, Global Knowledge Instructor, Dealing with Specific Types of Difficult People - Global Knowledge's Expert Reference Series of White Papers