You don't accent.
You use your wrist on the first, fingers on the second (When speed increases).
You count & 1, & 2, & 3, & 4 (This helps make the second as loud as the first...hence sound the same).
Though I'm sure Ranman tells a good way too, I was taught to accent the second stroke at slow to moderate speed. The accent drops out naturally at higher speed, becoming less pronounced. The accent will give forward momentum and an almost machine like precision to the double stroke. Some practice should be done on soft surfaces like a cushion or your knee so as not to rely on rebound. Doing so will make the double stroke burn when you get on the drums.
The first stroke is wrist, the accented second stroke is whipped with the fingers. This works for me.