Yes. You can sign the binary the same way Microsoft, or anyone else, would sign the binary. At that point, you need only to add your public key to your key data

Yes. You can sign the binary the same way Microsoft, or anyone else, would sign the binary. At that point, you need only to add your public key to your key database and are good to go. Microsoft has no way to prevent this (short of requiring vendors not to allow people to add keys).