Seeking advice on inducing lactation (breastfeeding kind)

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A good friend is having a baby but can't breastfeed because her nipples are inverted. I breastfed for 3 years, ending December 05. Is there any way I can induce again (without getting pregnant!) I imagine it hasn't been THAT long so maybe it wont be too hard. She would want me to pump milk for the first month or two of the babies life as supplement to the formula she's giving. I'm healthy and have a clean diet so I think the risks are minimal. Any advice? Ever done this? Thanks.