so it connects via USB..
First of all we need to find out if is being detected properly..
cat /proc/bus/usb/devices
Above will show all devices connected to USB bus, if your modem is detected properly then you should see Vender ID and serial Number under one of the bus.
now need to probe device:
modprobe usbserial vendor=<vender id here> product=<ID here>
After that run wvdial configuration.
You can follow this
CDMA wvdial how guide to for that !
If it above not work for you then there are other method I found..
See :
http://oozie.fm.interia.pl/pro/huawei-e220/
http://codepoets.co.uk/t-mobile-webnwalk-aka-using-huawei-e220-usb-modem-linux
http://www.draisberghof.de/usb_modeswitch/