umts/3g modem configuration problem

[farinet at arcor.de]

Since for the moment, i do not have a cable line i got a 3g/umts/hdspa+
usb modem, a tp-link ma180 but i'm unable to get it to work.
network-manager or wicd do not recognize it at all, apparently. Ceni
sees a wwan0 but is unable to set it up.

I found a thread in askubuntu
(https://askubuntu.com/questions/268264/how-to-install-tp-link-ma180-on-ubuntu
- the solution there seems not completely correct, but some info was
useful - at least the modprobe command given there has some effect, but:

$ sudo nano /etc/rc.local
    sudo modprobe usbserial vendor=0x2357 product=0x0201

seems at least doubtful to me (a sudo in rc.local ???).

Anyway, may be someone out here really skillful would be able to give me
some pointer.

Thanks a lot in advance!