Enable USB debugging through recovery mode and ADB sideload

This is a follow-up question to Apply update from ADB: how to use it when you are locked out of the device. Basically, I intend to somehow use this command to remove the lock screen:

adb sideload customROM.zip

But, the customROM.zip should be something like described here to enable USB debugging. The problem is, those steps are incomplete:

Steps to Enable USB Debugging Using Recovery Mode

• Unzip the stock ROM.

• Within the extracted folder, you will find the system.img well extract it too using Ext4 Unpacker

• Also, extract the Update-SuperSU.v1.65.zip file.

• Now open the folder where you have extracted the system.img files

• Grab any .apk file from this folder and change the extension from .apk to .zip

• And Copy the RSA Certificated to the Update-SuperSU.v1.65 folder (delete previous files if exist)

• Also, copy the build.prop to the system folder located within Update-SuperSU.v1.65 folder

• Locate the update-script file within this folder and edit it using Notepad++

• You need to update the build.prop file after adding the following line at the bottom
  persist.service.adb.enable=1

• Next step is updating SQLite Database

• Which can be done by adding the following code to the update-script file
  sqlite3 /data/data/com.android.providers.settings/databases/settings.db "UPDATE global SET value=1 WHERE name='adb_enabled'"

Cheers! You have Enabled USB DebuggingNow you can install your custom or stock ROM using ADB – USB Debugging

Although the above steps seem incomplete, they look convincing that there might be a way to modify a stock ROM to enable USB debugging by:

adb sideload modified-stock-ROM-which-just-enables-USB-debugging-and-does-nothing-else.zip

Is there any better explanation than those steps?