I know you can a make a female lactate by useing breast pumps regularly even if she is not pregnant. For example 10 minutes a day. I know people who have tried this and said that it took about 3 months to start lactating.
However not all men can lactate and this isn't off wiki I just covered this in biology lol. In most men their is little to no mamory tissue and so the ability to lactate is impossible. Nipples are a through back to when we develope in the womb. We all start off as female and develope from there etc.
One way to make a man lactate is to give them a female hormone supliments. This isn't a great idea as all sorts of problems can occur and I should think they would be pescription only. Taking female hormones could result in enlarging breast tissue ie growing boobs, not the best look for a guy.
How you tell if a man has mamory tissue of not I don't know but I am guessing it is unlikely a man could lactate no matter how often breast pumps are used.
Hope that helps some
