You will get this naturally while working on the multiplayer trials, but there is a quicker method to get this if you have a partner.
Basically, it boils down to getting 5000 points when reviving someone, but only losing 1000 points when you are downed.
Start a private game, inviting your partner into it. From there, find an escalator. The person earning the points waits at the bottom, while the helping partner runs up the escalator and repeatedly walks off a ledge. If you don't have too many health boosts, your partner should be downing themselves in about two jumps. Revive. Repeat.
(Note: hurtling over a rail doesn't cause you any damage, so you have to find an escalator with a small area at the top you can walk/jump off. Try not to land on anything on your way down).
You should be getting about 80,000-100,000 points per person helping in a day (with your partner losing about 16,000-20,000). On day two, partners can switch up. For two people switching each day, that 80,000 points per person in the session (when you normally average 25,000-30,000 per person a session). If only one person is going for the achievement, that's 160,000 points per partner in the session.
As a bonus, you'll get all the multiplayer revive trials done!