You wouldn't have to have an outside facilitator -

See this example - BPD Support of San Diego (La Mesa, CA) - Meetup
And this - Shades of Grey BPD: NYC (New York, NY) - Meetup

These people do have an organizer (who is someone with BPD), and they meet in real life and confidentially share experiences and support each other. In that way it's similar but not identical to a 12-step group.