Take it as a given that we communicate as much or more through body language as we do through the words we say and our tone of voice. Here's some quick thoughts on body language and how to convey TRP-style dominance and confidence with it.

First principle: you wanna take up space. But it's better to look aloof and relaxed than "at attention", military-style. (The exception would be if there is some reason to be "at attention.")

In conversation while standing, imagine a line going down the middle of your head down between your feet. You wanna lean 5 to 10 degrees BACKWARD from that line. Hold your shoulders squared -- I repeat, do not slouch unless you want to be perceived as weak. Chin up a little -- not exaggerated like Obama does in his photos, but better to be that than tucked in like a boxer's. Don't stand around with your hands in your pants pockets. Leave your arms hanging naturally at your side, and use hand gestures very sparingly.

When sitting, it's okay to lean BACK but not forward. You can put an arm out on the sofa, kick your legs out -- all dependent on the social situation. In a job interview, it wouldn't be appropriate to lean back like that, but it's a different situation when you're chilling with a girl at your house.

Walking: again, shoulders squared with a slight lean back. When you're walking forward you don't need to lead with your head. That'll put you into a forward slouch. Keep a straight spine, keep your movements graceful and deliberate. Pretend your head is a bowling ball on a stack of plates -- if you let it dip, the bowling ball will fall.

Your face: don't smile for no reason. Don't. Smile. For. No. Reason! A neutral, relaxed face is best. Don't open your eyes super-wide. Meet people in the eyes. If you don't look people in the eyes when you talk to them, you might as well hang a sign around your neck that says "I'm a Loser".

Do not take rapid actions. When you go to pick up a cup of coffee, take out your phone, or open a door, do it at half the speed your brain "wants" you to do it at. Good. Now do it at half the speed of THAT. Now you're getting there. Relaxed, deliberate, graceful motions are attractive. Fidgety, nervous motions are the behavior of a weak man whose system is flooded with chemicals he can't control.

Now remember that center line going through your body? Don't let your limbs cross that. Meaning, if you are passing someone the sugar at the table, don't let your right arm cross over your chest to pass to your left. Instead, transfer the sugar from your right hand to your left hand in the middle of your body, then pass with the left hand. When you cross your own center line your take your shoulders off the square and start slouching again. (This is a piece of advice I got from a showmanship book for magicians. If you go back and look at real showmen like Johnny Carson or Dick Cavett, you'll notice they follow practically every piece of advice I've laid out here.)

In brief, a dominant man is RELAXED because he knows his dominance is assured. He takes up space, is aloof from the petty details and vigilant towards things that deserve his attention. And he never lets his relaxation take him off his guard so as to compromise his dominance.

[Thanks to /u/Sufferix for asking about this in a comment. My reply became this post.]