Manually setting Storage Options

I am using aws-amplify to build a web app.

I have decided to create a custom UI for the login flow, and capture the authentication data in a redux layer. Unfortunately, I lose access to some handy premades such as withAuthenticator which makes Storage work automagically.

Through examining the source code, I found StorageOptions to be what I need. I'd like to be able to pass in my credentials manually, to support my custom UI. Storage is an exported class from the aforementioned library.

How would one accomplish this?