Implementing Authorization Code Flow with a custom user agent

We are in the process of evaluating Auth0 and we are wondering if there is a way to implement the Authorization Code Flow using a home-growth web user agent.

We have an application that functions is able to behave as a web browser and we are looking into having it interact with Auth0 so we can automatically respond to the login/authorization prompt on behalf of the end user without the need to have the user being prompted to enter that information.

None of the other flows described at will work for us as we need to be able to receive and Authorization Code in order to request an Authorization Token

Any insight will be appreciated.