wvdialconf is completely non-interactive. You still need to edit /etc/wvdial.conf to specify the phone number, login name, and password of your internet account in order for wvdial(1) to work.
It is safe to run wvdialconf if a configuration file already exists. In that case, only the Modem, Baud, Init, and Init2 options are changed in the [Dialer Defaults] section, and only if autodetection is successful.
Also, there is now a mailing list for discussion about wvdial. If you are having problems, or have anything else to say, send e-mail to <firstname.lastname@example.org>.
An exit status of 0 means that a modem was detected and the configuration file was updated successfully.
Any other value means that something went wrong and the configuration file was unchanged.