Treat it very much like a Bloody Versus:
Both sides make statement of intent. Both make their dice pool, narrate the action, get any bonus dice from roleplay, and then...
Make the opposed roll; the winner is counted as the Body of Argument (BoA), and the difference is the remaining BoA. (A broken tie is a Win with 0 remaining.)
Exempli Gratia
#Exempli Gratia Fred (playing Burt the Bad) and Vel (playing Sammy) are arguing over which way they should go. Fred wants to go left, to the caves, Vel wants to go right, to the keep. The rest of the group is undecided. Fred's got Oratory B4, and FoRKs a die each from Intimidation and Threat-Wise. Vel has Ugly Truth B5, and FoRKs in a die from Cave-Wise, and asks for a bonus for Joe's Paranoid trait.
"'We should go left, to the caves. It's obvious that the keep is manned, and thus more of a threat, plus, if you go right, I won't help you fight. And that would be bad.' I then finger my sword hilt," says Fred.
Vel rebuts, "I point out that Burt's being intimidating, doesn't know diddly squat about keeps, and just wants to take us where he can kill us all and take our stuff. 'Our friendly murder hobo is asking you to go into the dark, to trust him, and face god knows what monsters — in this region, bears are likely. If we go to the keep, at least we'll be able to see threats. By the way, I'm hungry, anyone got some Jerky?"
The GM grants the die for Joe's paranoia, but no others. Fred rolls 4s, Vel gets 6s.
Vel wins, with a margin of 2s. Which means a 2 of 6 remaining... compromise time. The go to the keep, but if things are hostile at the keep, they'll flee back to the caves.