i think this is a racing question as opposed to a drifting question.
this is a difficult question to answer as i have never tried to think about it too much as 's' corners can be so varied, the perfect line varies also. my first suggestion would be to just try several laps with slightly different lines, find which works best (by lap time or by whatever feels best to you). if you really must think, then i can suggest a starting point. after the first corner, make sure you car is positioned in the middle of the track, and turn in for the second corner approximately half way between the apex's of the two corners. if i've not explained my self very well, i will do a diagram.