During "incidental fire" you could read a person to see what his body language is saying, act under fire to keep your cool (digging in to endure fire), you could read the situation to gain advantages (position of the sun, dust, enemy's location, etc), and all of these could grant or remove bonuses to you or you opponent.
Then when it comes time to shoot, if it's PC v. PC, couldn't you have them both roll +quick and whoever rolls the highest makes his shot? On a tie, you both get shot.
If it's a simple duel to first blood, you're done. If not, you keep fighting using the normal rules.
Also, Vx suggests that PCs be allowed to make independent, say, Seize by Force rolls, and then both roll+Hx to interfere with each other. So the 'clunky' route seems to be the 'official' way to go, if you're interested in that.
Hopefully you get something useful from all this text! :)