I had the same idea a few weeks ago. I would have really liked to implement this feature into the current internet radio applet but the sources are not available. I have asked about opening the sources on the developer mailing list, the answer was to file a bug request. I have not done it yet, but I will definitely file a request for opening the sources when I have time.
In the meantime I have implemented a rudimentary alarm home applet in python. It needs some bug fixing (e.g. sometimes internet radio is not starting) and I need to package it but I hope that I can release it in the next few days.