I do them exactly like a clean, except I don't squat underneath it, when I reach full extension, I relax the elbows and let the bar travel as high as it will, which is belly button level, sometimes slightly higher. Instead of pulling myself underneath at this point as in a clean, I come back down flat footed as the bar falls, bend at the knees to absorb the weight, and then reset for the next rep.
Here is how I clean...I pull like a deadlift from the floor to mid-shin, then I pull like an RDL from mid-shin until my knees are straight, the bar is near mid-thigh at this point, then I rebend the knees and jump shrug, the bar makes contact with my thighs, but I don't drive into the bar and knock it off path, all the force goes upwards into the jump shrug. When I reach full extension, I relax my elbows (which are tightly locked until this point). As I relax my elbows, it allows the bar to get to about my belly button, once I feel like the bar is there, I pull myself down into a front squat as fast as I can while making a conscious effort to whip the elbows around as fast as humanly possible.
For me, the most important thing is not to relax the elbows until full extension, doing so early will zap a huge % of your power. If I did that, this would have been like trying to upright row 375, which for me aint happening in this lifetime.
Keep them fast and snappy. That is why I love jump shrugs so much (other than the trap growth from them) they keep you thinking about speed. If your clean pulls look like a cheating upright row or a slow shrug with momentum, then you need to relearn the form.