I think women have an extra hurdle between them and swinging, namely our own and society's attitude toward "sluts." Our partners can really help with that by being open, approving and encouraging about whatever direction our sexuality takes. That is probably the most important step, after talking openly and often, toward women feeling empowered enough to consider swinging.
For many of us, it's not so much needing others as having a shared activity that enhances our own relationships and amps up already terrific sex.