Currently, there are only two regen settings, and due to the complexity of changing them on the touch screen, it’s almost impossible to safely change them while underway.
My Chevy Volt also has two settings, but they are easy to select while driving. It’s quite fun and useful to do so, much like downshifting. The ideal scenario would be a system like the Volkswagen e-Golf, which has paddle-shifters on the steering wheel that select four different regen settings. Leave it to the Germans to achieve the ideal when it comes to driver involvement.
Even better would be a steering-wheel-mounted thumbwheel that would infinitely vary the regen, much like the pitch-trim controls on aircraft.