Is there any reference about adding my own base pass and scene texture in 4.22+? Help!

Unreal’s rendering pipeline is refactored since 4.22, but Epic’s documentations about their rendering pipeline is really not helping.

What I want to do is add a custom base pass(using FMeshMaterialShader and FMeshPassProcessor) by modifying engine and integrate its output to the material editor’s SceneTexture node for my teamates.

Thanks to the lacking of documentations, I can’t figure it out where to start implementing even though researching engine source code.

If you know any helpful article/documentation/implementation, please let me know too - It will be a great help for my small team.