Use the pedialyte instead of water to mix dry KMR. Or just add some to the liquid KMR with each feeding. When it says not to dilute it, it’s talking about the best way to use it for a human. I don’t think the manufacturers really considered that it would be used for orphaned pets. It increases your new baby’s chances at survival by helping to balance his blood chemistry and making it more likely that he (or she) will stay hydrated.
If at all possible, carry the wee one around with you as much as you can. Put on your hoodie backwards and nest him into the hood. Or make a sling out of a scarf of piece of fabric. The idea is to keep him close to your warmth and heartbeat which will make him feel secure and will help keep him from crying so much.
When you got the KMR from the vet, did you take the kitten in? If not, do call on Monday as ask if you can get an appointment. The survival rate of hand-raised kittens isn’t as good as those fuzzbabies who still have their cat mamas. You want to give this little cutie as much chance as possible.