I've been thinking about this today as well. My thought is that what you'd want to do for arpeggiation is define a patch where the expression pedal controls the pitch, and the heel and toe positions are set to the lowest and highest pitches you intend to use in your sequence – an octave below and an octave above, say. You'd then use the sliders to set the pitch for each step in the sequence individually. That's probably a somewhat laborious process; the good news is that once you've got it figured out, you can save the sequence as a preset on the 8-Step.
LOTS of interesting potential with that box attached to an Eventide stomp. I'm personally interested in using it as a way to get square-wave modulation of loop times, producing loops that jump in pitch at intervals unrelated to the loop content. I've seen David Torn do that with a PCM 42, and as far as I can tell that's the only device capable of that particular sound.
