This is from page 103 of the 8.3.2 Product Guide. I knew how to find it by searching for the word 'switch', since I've had to send this to other customers as well:
Switching authentication methods during a logon session
The firewall allows you to use multiple authentication methods for a given access control rule (for
example, users might use RADIUS or Password for Telnet authentication). When logging on, a user can
change to another authentication method by typing :authenticator after the user name.
That's the name of the authenticator you created (not the word 'authenticator'). So for you a user could type 'swadmin:testowa' as their username and then enter the password for the testowa authenticator instead of the password for the default one, ADMOJE.
I'll paste this into the SR you just filed also and you can let them know that this works so we can then close out your SR.