I just wanted to add that in my circle of friends we actually call them Mother Blessing Ceremonies instead of Blessingways to be politically correct.
While some of what we do might be loosely based on the Blessingway tradition, we are not part of that tribe and our gatherings are very kind-veggie-rainbow-crunchy-granola-hippiechickie-american. I love the book Mother Rising and find it very helpful for planning a ceremony like this. We henna the belly, tell stories, sing, give footbaths/massages, give gifts for the mother (like birthing beads or postpartum gifts), and bring frozen homemade breastfeeding-friendly food for the mama after the babe comes. We bless her and love her and have a lot of fun and take a lot of pictures!
Although I agree with sapphire that you can just invite your friends over and let them bless you, it is very nice to have a designated "hostess" (even if its at your house, which is often a great choice) to direct the flow of the ceremony, so the pregnant mama can relax and enjoy, and not be the one running the show.