A truly splendid creature
Might be hard to retain possession if she likes it too much, but I think I'd be willing risk that/accept that challenge myself, too.
Baby steps. If she wants to try more than one guy, do it. Move on to getting her the gang bang she wants. Show her off to black guys and let her pick one she fancies. If she is never around any, it won't seem natural or come easy. Just make sure you take her to bars and clubs where they hang out in some numbers. It would probably be too intimidating to start out where she is the ONLY white lady, and you might lose control of the situation. They like to share with each other anyway, so you wouldn't have to work on that part of it.
Best of luck to you getting her thoroughly blacked, and best of all, getting her onboard the process!