i have heard that homemade detergents are not a great choice for cloth diapers, especially given the amount of borax used. the following is from pinstripesandpolkadots.com recently asked questions page:
"The problem with the homemade washing mixture is....[that the] soap reacts poorly in hard water conditions and creates a scum or film that can be left on the clothing. The Borax and the Washing Soda are useful as water softeners to reduce the forming of soap scum however, they can form their own precipitates in hard water that can be left on the clothing or washing machine and cause difficulties. The borax can also be abrasive to fabrics in certain situations and is often considered harsher than necessary for washing.

So unless you are washing completely natural fiber diapers in completely and naturally soft water, using a homemade washing mixture will probably cause you more diapering headaches than its worth."