Okay, I was mistaken. :( You're right about Eevee's only learning wish as an Egg move... I don't know why I read the pokedex wrong, lol. The only way I could find to get wish onto Eevee was through this breeding chain:
Togetic -> Pikachu -> Eevee
Which means, you level up a Togetic to get wish, (Make sure your togetic is a male!!!!) then breed it with a female pikachu. Level up your resulting (Male) Pichu until it becomes a Pikachu, and then breed it with your Eevee. A few things you need to keep in mind: It has to be a Togetic, because babies can't breed, and Togepi is a baby. In Fr/Lg, togetic learns wish at lv. 29, while in Ru/Sa it learns it at lv. 31. It absolutely HAS to be a male Togetic, because egg moves can only be learned through the father (unless it's with a ditto, in which case I'm not sure, lol) And your resulting Pichu MUST be male and MUST have wish, for the same reasons. Your Eevee MUST be female too, btw. If it isn't you'll just have to breed it with a ditto until you get a female. :( The same goes if your Togetic isn't male. You'll have to breed for a male.
Just to help you out, you can get a togepi egg from the old man on Chrono island in Fr/Lg. To get one in Emerald, you have to trade. To get one in Ru/Sa, you have to trade from Colluseum, and in Colluseum, you get one from the E-card room. Good luck! I hope your Eevee turns out great!