As I said on that page, you can make a neem leaf insecticide by crushing and steeping neem leaves. It's not as strong as neem oil but it works.
Use cold water and steep the leave over night, rather than boiling them as some people may be tempted to do. Boiling, in fact, any heat, destroys the active ingredients.
Great web site! We are interested in using the neem leaf extract for our 23,000 sq. ft green house, so need large quantities of foliar spray. We commercially dry other leaf products via air confection and we're considering drying the neem leaves, then making a powder for a shelf life and easier application. Would apreciate your comments, thank you.