It's much easier than you would imagine. You need not use "wvdial"; the KNetworkManager works like a charm. This should work the same for other plug and play 3G modems by Sri Lanka Mobitel and Dialog too.
First; plug in your MF100. Kubuntu would auto detect the modem and show a mobile icon in the system tray. If you are already connected to a network, the icon would appear in the context menu of the KNetworkManager like below.
Click on "Mobile Broadband - Create network connection" to get the following dialog
Fill the information as follows:
Connection name: any name
Connect automatically: check "Connect automatically" if you wish to establish the connection automatically when you plug the modem
In the Mobile Broadband tab:
User name: anything but blank
Password: anything but blank
APN: "mobitel3g" (without quotes) for Mobitel. I think for Dialog it's www.dialogsl.com please verify.
Type: Any (try "Prefer 3G" or "3G UMTS/HSPA" if you have better 3G reception
Leave other fields as they are.
In the PPP tab:
Check "PAP" under Authentication and de-select every other option.
Click OK to save settings and connect to the internet, and if you did not use auto connect; you'll have to click the icon in the system tray to activate the connection.
It's that simple! :)