What you should do is first breed for the perfect IVs of the Hidden Power spread, let's say you're doing Ice so you want the IV checking guy to tell you that HP, SpA, SpD, and Spe are perfect, you also generally want him to say their overall potential is relatively superior when doing so (this means that both Atk and Def are low). Then when you hatch something with outstanding potential and perfect stats in the ones you want, you know that either Atk or Def (or both) are high, and that you've probably inherited the 30 IV in one of them. You can take the hatchling(s) to the Hidden Power checker and see if it has the type you want, if it passes that then you go to the Battle Institute and
save your game (so you can reset and leave the institute, otherwise you have to do 5 battles in a row). You then enter your Pokemon in a battle there and it will be instantly scaled to level 50 and you can check its stats in-battle. Confirm the IVs with an IV calculator (
MetalKid's is my favourite) and you'll either see that your Pokemon has 31/30/x/31/31/31 (bad), or 31/x/30/31/31/31 (good). Keep doing this until you get the spread you want :)
Getting someone to check the IVs with KeySav can be great for you but tedious / annoying for the person helping you, so learning to check manually yourself with the info you're provided with in-game is a good thing.