how do I make a custom boot?

[colonel]

well, you can flash with a blank ms.nbf which is the ExtRom. This will remove all of the Verizon ExtRom cabs. You can learn to make your own ExtRom in the Sticky thread. As far as your settings, aside from building your own rom, you can create a cab to make these changes for you and either put it in you custom ExtRom or run it manually after the hard reset.