It's easy once you get the hang of it. To initiate it, I do the scandavanian flick. Do that then quickly countersteer, but you gotta be quick on some cars. Instead of using the wheel to control your angle, concentrate on throttle control, using it to control the angle of the slide. Catch the slide by gently letting off the throttle and bring the car back in line by rotating the wheel straight again while fighting the force feedback, but don't let go of the throttle or the car will spin out. If you're too late bringing the wheel straight again you'll start to fishtail.
To do a sequence of drifts, as in drifting one way and then the other like in an S-curve, at the end of the first drift you let off the throttle and tap the brake, that will swing it the other way. Let go of the wheel and let the FFB bring it the other way but catch it before it goes to full opposite lock and apply some throttle right after the car swings the other way to catch it. It's only a matter of holding it. You can drift on straightaways that way and do a whole lap sideways on most tracks.
Well, that was my take on explaining it. English isn't my first language so if someone knows what I'm trying to say, I encourage you to clarify or correct me.
