http://nuggetbridge.com/breeding/breeding-perfect-pokemon-x-y/
Try following this guide or here is simple version:
1) Find parents, one with correct nature, one with a perfect iv. You can use Safari Ditto for the latter
2) First breed: Use everstone on one to get correct nature and use power item(power lens,etc) to get perfect iv from the other parents
3) Second breed: get the child of First breed give it everstone and find another Ditto with another perfect iv and give it another corresponding power item and breed them again.
4) I cant remember exactly but child pokemon will take 3 IV from their parents. Meaning with baby from First breed having at least 1 perfect iv and Second ditto another 1 perfect IV, there are chance that it will get both perfect IV from the parents.
5) You will need to hatch several egg till you get one with 2 perfect iv.
6) Now get that baby and breed it with yet another ditto with another perfect iv with the baby holding everstone. However let the ditto now hold destiny knot instead. Reason is it will be very hard to hatch an egg with 3 perfect IV from its parents while the baby only get to randomly pick 3 IV from the parents. Destiny Knot help this by allowing the baby to take 5IV from the parents instead and therefore increase the chance of inheriting the 3 perfect IV.
7) Repeat this process with new baby that have 4 IV and 5IV...ofc the more perfect IV you want the more egg you need to hatch