OK so I'm back at this issue
Creating a modified authentication process realized I needed to tell UserAuthenticatedEventArgs my Authentication Type
var eventArgs = new UserAuthenticatedEventArgs(user, msIndividual.emailAddress, loginStatus, "myCustomAuth")
But now when I try to logout it fails. I'm sure I'm missing something probably simple but the error I get back is
System.InvalidCastException: Unable to cast object of type 'ASP.desktopmodules_myCustomAuth_logoff_ascx' to type 'DotNetNuke.Services.Authentication.AuthenticationLogoffBase'.