A way to create a semi-random waveform is to route a random waveform and say a sinusoid into the input of an AmpMod module. Multiplying the two functions as a gain controller thus imposing the characteristics of one signal onto the other. The noise waveform can also be used, perhaps after it gets some lowpass filtering to reduce the sharpness and after an A->C module to convert it from audio rate to control rate.
