Searching the forum for ways to duplicate the BV6 InputBox control it looks like a way to do it is with a Dialog using FormsBuilder to create the form. I have downloaded and ran FormsBuilder and it looks very promising. Is there there a collection of jason files to use or is the only option creating them?
If you are looking for a single input field then consider using B4XDialog with the input template.
If you want to build a "form" then it is very simple to do with FormsBuilder.