This is super easy with the new co-op mode. There's no limit to how many heroes can play at one time like the other modes.
I usually go with an officer to build up BP quickly, then switch to a hero. General Grievous in particular is good for his Unrelenting Advance skill. You'll frequently spawn right behind enemy bots attacking a command post, and I'd pop that skill and get an almost instant killstreak of 10-12, because the bots are dumb.
I went from 17 hero kills in my first 2 months of multiplayer to 398 in my first 3 hours of co-op. Not having to worry about humans trying to kill you makes it so much easier.