I don't know wether somebody has posted something similar but I hope this will help

I am using ubuntu linux 8.10 (Intrepid Ibex) with the Huawei E170 usb modem supplied by MTN.

If you are also using ubuntu 8.10 then things are a bit more easier. The following steps are what you need to do.

1- Right click on the network icon on the top panel and select "Edit Connections" this will bring up the network connections window

2- Select "Mobile Broadband" tab

3- Click on "Add". A wizard (druid in linux) will come up

4- Select Nigeria from the country list and you will get a list of mobile operators in Nigeria.

5- Select MTN , click "Next" and "Apply"

The next time you left-click on the network icon on the panel you will get a list of connections. Select the one you just created "MTN" and you will be connected.

Now you are ready to start surfing.

If this didn't work or you are not using ubuntu 8.10 then you can try using wvdial utility
more info at http://a-ig..com/2009/03/mtn-3g-and-linux.html