if you can get her to watch porn. specifically armature porn. include multiple races and gender sets. Asian women with white men. black men with latina women. etc. evntually add in more black men with white women. you may also try to go to some sex parties or clubs frequented by black men. when there try screwing some black women if there are any there and encourage her to go black as well. you dont want to put all the pressure on her.
i would say primarily keep her away from professional porn.it may scare her away from actually wanting to fuck black men. seeing some small white women being torn in half by diesel or shorty is not lily to arouse her.
First of all, decide for yourself that this is what you want for you and the wife, and decide for yourself as well what your role would be should this eventually happen.
I have helped coached numerous couples into this lifestyle and one of the first rules I employ is for the hubby to first affirm that this is something he wants, that way he won't later change his mind because a lot of hubbies do eventually get cold feet and I don't trust a lot of them who just say they want this and yet are unwilling to pay the price for it to happen.