It's explained in the article. First quote:

> You want a covered pail partially filled with water to put used diapers in as soon as removed. If it contains soap or detergent, this helps in removing stains. Be sure the soap is well dissolved, to prevent lumps of soap from remaining in the diapers later. When you remove a soiled diaper, scrape the movement off into the toilet with a knife, or rinse it by holding it in the toilet while you flush it (hold tight).

> You wash the diapers with mild soap or mild detergent in [the] washing machine or washtub (dissolve the soap well first), and rinse 2 or 3 or 4 times. The number of rinsings depends on how soon the water gets clear and on how delicate the baby’s skin is. If your baby’s skin isn’t sensitive, 2 rinsings may be enough.

The technique hasn't changed much.