This solution is written relatively early, so there may or may not be a faster way. The quickest way of getting 98 vs games under your belt that i've found is to begin a heroes game with a boost partner. Have 1 person be an Umbrella op, and the other a Hero. Just simply meet somewhere & have the Umbrella op kill the Hero. The match ends when the Hero is dead. I personally found the Train Wreck map useful as there are several sets of exploding barrels in the Hero's spawn room. Simply have the Hero stand near the barrels, then run in, score 4 or 5 headshots with your pistol, then toss a grenade at the barrels. Our matches were taking roughly 30 seconds a pop, but factoring in voting & load times, the games took about 3 min each.