Take a bit of black construction paper or fine cloth and touch it to the underside of a male flower that has opened.
You should get some pale yellow dust. Just keep trying; you're more likely to snag some pollen if you get the flowers JUST as they open- catch it on the end of a Q-tip and use that to pollinate a few low buds on the females, and tag those buds with string so you know which have the seeds in them later.