Basic auth tokens config

I have just deployed tyk gateway for our apis. The apis supported both oidc and basic auth. I deployed tyk with oidc support, and now I would like to add basic auth support. Given a set of usernames and passwords, it would be nice if I could just create the tyk auth config directly on the disk before tyk starts, but from the docs I don’t have a clear sense of where the token.json file sits or how it maps username to password and policy. Is this data structure something I can set up on disk from the outset? If so, please provide some guidance.