I like this one too, so I took a look at how to build it in.
The basic version can be done pretty easily: build a chord, set the step to polyphony of 1 and have the pitch be selected at random from the chord.
The cost here is one variation of the multi-trigger mode, namely at the place where you specify whether one or all note-offs are sent for a multi-triggered step. I wonder what your thoughts are on this.