Customizing Skincluster Or Smooth Bind

[john-smith--44]

I'm trying to make a deformer works with some joints.
So I'm making a deformer based on skincluster, because I want to use skin weights and the UI of skin weight tool.
However, I could not find a way to modify deformer in smooth bind.

This is my question. How can I customize smooth bind skin deformer?

or How can I make a custom deformer using skincluster?