I managed to work out a custom login page, with custom logic

I can create a module out of it, as I developed the ASCX under DesktopModules, then use the "Create Module" at the Host setting

but I can't make/create this as Create New Extension as Authentication Provider, as there's no similar interface allow me to point to the ASCX

apart from developing it through Chris module template, and install separately, can it be done through just like the Module?

authentication providers are different to modules ... they extend from different sub classes and are registered with dnn differently