This is the original article I adapted my method from: http://forums.longhaircommunity.com/vbjournal.php?do=article&articleid=95
I use the foam now since its easier on straight hair, but on locked hair I found it a lot easier to use the squirt bottle with liquid to target it down to the scalp. I also would dilute the recipe in twice as much water, skip the lemon/lime juice because it made my hair too soft and slippery with it, and typically needed 2-4 oz. of liquid per wash. I left mine on 5 minutes or so in the shower, then rinsed. It rinses quickly and cleanly unlike a lot of other things I've tried. Adjust accordingly for how much hair you have.
Other things I've tried is extracting the soap with tea which you can play around with for all sorts of different benefits. Chamomile tea helps if you find the soapnut liquid a bit drying, and peppermint tea based soapnut is great for scalp itchies or cooling off in the warmer months, along with a few drops of tea tree oil. Let us know if anyone gives this a try!