All you have to do is to Email your redirector prefix to Third Iron support team (support@thirdiron.com) asking to update your authentication to OpenAthens. They will use your redirector prefix to configure this in the back end of your BrowZine setup You do not have make any custom settings in OpenAthens to support this. 

To look up your redirector prefix: access the administration area as the domain administrator and navigate to the redirect link generator (Resources > Redirector link generator).

The part you are interested in is the bit like this: https://go.openathens.net/redirector/yourdomain.com?url=