This thought just crossed my mind:
Set the web login page as the default for guest registration. Guest hits page and clicks the link to go to registration. After registration, when the guest clicks login, we send a CoA to the controller and disconnect the user, the device reconnects and the captive portal page is displayed again at the login page. Guest logs in and put into the guest role.
If this is a feasible option, how would the service rules be different for the two different types of login?
If there is an easier way, please let me konw.