Many people have been able to do this with Tier Two drift cars like the Mazda RX-7 Type RZ, but it can be a little difficult to do that. I personally recommend using a Tier Three drift car like the Chevrolet Corvette Z06 or the Viper, which worked a lot better for me.
Set-up a custom drift event on Okutama - Tenshi Way, with unlimited flashbacks and the Tier Three car of your choice. You want to aim for this achievement during the second or third hairpin turn. Go in with a very high speed, and get as close as possible to the first pylon hopefully getting a x3 multiplier. Because of the speed and the power of the car, you should be able to make it through the turn without breaking the drift adding an additional x2 multiplier. If you spin out or collide with something during the middle of the turn, make sure to use your flashbacks until you get it right. Just keep practicing and this should be the easiest method to get this achievement.
Depending on your multiplier, you will need at least this many points:
62,500 x 4 = 250,000
50,000 x 5 = 250,000
41,667 x 6 = 250,000