After installing the update, I got this after getting one kill from the base. So I can confirm. YOU DO NOT NEED TO DO THIS IN THE SAME MATCH. As long as you've killed two enemies while sitting in a hostile capture point across all of your games, you'll get it as soon as you do it once after installing the update.
Now, how did I do this? I did this with the Chinese NC-31 (the free tier I tank). The stock gun in this thing causes substantial damage, has high penetration, and reloads very quickly. It also has some fairly solid armor; it's the complete package! When you start, don't go for the base immediately, although if you're playing tier I's, chances are your opponents aren't too skilled. You'll want to dwindle the enemy force to down to one or two, and then go for the base. Once there, put your back to the wall and wait for one of the remaining enemies to come find you. If you hung back while the rest of the team was obliterated, you should have a good amount of health, and all you have to do is rain the fire.