Trust me: the only way this can work is if your wife really wants to do it -- if the idea turns HER on, too. If it doesn't, don't push it. You cannot talk her into it. Trying to do so really could damage your marriage.
When both members of a couple want to do something sexually unusual, it can be great. When only one does, it can be disastrous. Take it from someone who's been through this. If your partner isn't interested, then you have to decide how important this is to you. If it's hugely important and you think you can't just enjoy the sexual relationship you have now, that masturbating to your fantasies isn't enough, then you'll have to end the marriage and find someone who's more sexually compatible with you. However, you should seek therapy, preferably from a specialist in marital sexual issues, first.