First time tried and successful:
MA/SR Scrapper. I use Storm kick, Dragon's tail, Eagles Claw, Cobra Strike, and Crane kick with Muscular Alpha and Diamagnetic Interface. I also use Support hybrid for the END discount. I know my attack chain isn't optimal for this sort of thing, but my playstyle has all my attacks set to Target the nearest enemy and then trigger the attack. It makes it fun to jump into a huge pack of mobs and watch my soft controls (stun, knockback, etc) take mooks out of the fight while I just switch to the next target for the next attack. When they wander back, I rinse and repeat.
Time: 9:45
193 DPS
It might have gone faster if I had not spammed attacks so hard that I neglected to allow my Practiced Brawler to autofire. I got hit and knocked back three times.
Pretty neat experiment though. I used to read about Scrappers doing this on live, and I never thought I could ever actually pull it off.