My method is as followed.
1. Catch Ditto until you one that has the IVs you're looking for. More than likely you'll need to obtain two different Dittos.
2. Breed that Ditto with Pokemon you want perfect IV on, holding power item that passes that specific IV. Example Power Brace passes Att, Power Anklet passes Spe ect. Breed that Poke until you gain the nature as well.
3. After you gain that first poke with the first perfect IV and wanted nature. Breed it with the second Ditto with the second desired IV. The Ditto holds the Power item and the Poke with the perfect IV and nature holds an Everstone to pass the nature.
4. After a few eggs you'll gain a baby with the two desired IVs and Nature.