Let me start by letting you in a few breeding mechanics--
- Pokemon will pass down their nature if they hold an everstone
- Pokemon will pass down a stats IV if they are holding the corresponding power item
- Pokemon will pass down 5 IVs instead of the default 3 if they hold a destiny knot
- Pokemon have a 60% chance of passing down their hidden ability when bred with a Ditto. Without the Ditto only female Pokemon can pass down a hidden ability, and female Pokemon have an 80% chance of passing down their ability.
- Two power items will cancel each-other out, however the destiny knot can be used in conjunction with power items.
With that said, you need to juggle breeding with everstones, power items, and destiny knots. It will take time, but I assure you it works. You'll need a collection of Dittos that collectively have the right IVs you want. I would advise taking these steps~
- Breed for a Pokemon with the desired ability and nature.
- Give this Pokemon the everstone and breed it with a Ditto holding the power item associated with the stat you want to pass down.
- Give the new Pokemon the everstone and breed it with a Ditto holding a power item for a different IV that you want to pass down. Do this until you get a Pokemon with the right ability and two perfect IVs.
Personally what I would do from here is this...
- Make sure the offspring from the last step is female.
- Repeat the above steps to produce a male with two perfect IVs that are opposite to the female and give him a destiny knot. Breed until you get an offspring that would be better to breed with the Pokemon you already have, passing along the destiny knot as needed, until you get your desired Pokemon.
There are other ways to do this, however. My way may not be favored by others. For more information I would like to refer you to an external site, Smogon forums. Hopefully this link is allowed, because it explains what you are looking for very well.
I hope this helped!