I've read some about the process, but from what I understand the results are often unstable and unreliable. Soap requires fairly precise measurements so you have to calculate the saponification values of the types of oil you use in relation to the sodium or potassium hydroxide that you use. If you can't rely on the strength of the lye, you have lost the calculations before you begin and will wind up with a useless goop.
If you know of some good literature on the process, please pass it on.