Here's detailed explanation: after you get your KV, there will two files. One will be KV.Bin - and the other will be CPUKey.txt
With the cpu you need to convert it to .bin
What you do is down a program called HxD (Hex Editor) after you download that open files with it and select your cpu key file, after you've opened it click file save as. Save as CPUKey.bin.
Once you've done that click and drag both files into HDD: on neighborhood and then turn on 360, it should flash to the nand by itself and boom, you're set.