To induce lactation, the breasts basically need as much suckling as a newborn would provide, we're talking 6-7 or more times a day, initially for 30-45 minutes at a time but then once the milk starts coming in you don't necessarily need that much time. How long it takes to start flowing depends a lot on the woman, but it can definitely be done.
Despite what you might read online, while inducing lactation can often stop a woman's ovulation it is not an effective method of birth control.
There are a few sites out there to help guide people through it, but not a lot of good porn or other resources devoted to it.