I cannot help you with wvdial, I have used this rarely looong ago for simple dial-up (no 3G/4G). NetworkManager itself (not its applet) does not depend upon any GUI part and nmcli (command line) and nmtui (ncurses text interface, roughly equivalent to nm-applet) are included in the package. NetworkManager depending on Modemmanager and usb_modeswitch, it would be easy for you to manage your 3G/4G dongle.