it is in the repositories, but you need to enable extras-devel i think, or extras-testing. do so at your own risk. i think only ussd-widget is in the repositories, you need to download ussd-pad from the address there.

please note that PR1.2 will be available in a few days (might be tomorrow), and it will allow you to use the phone application to make ussd queries. so the ussd-pad will become more or less unneeded. the widget on the other hand is very useful for checking your balance at all times.