My honest response would be that you bring home and socialize more oftenwith good looking, well endowed single men friend and couples. Create an environment of flirty chat and in few weeks, months she will come around to it but she may not even tell you. Just see her reaction. Good luck you and her.
If she doesn't want to, you cannot make her. She may also see you wanting her to do other men as you pushing her away. All you can really do is tell her how hot it would be and tell her your fantasies, and see if she is interested in performing any of them. Otherwise... the best you may get is some bedroom roleplaying that you are another guy.
I'm puzzled why do you want your wife to **** other men. If she's great in bed don't you want to keep her to yourself.
has to be her choice, if not, that is the beginning of the end
grant her the divorce and when free, she will.