Didn't even think about the Kalifornia aspect. #%&*$# shame
Just so we're clear, when I say power-shift I mean once you get to full throttle, you stay at full throttle and just bang through the gears. I always used clutch for upshifts, which I considered more crucial, and would downshift without clutch.
So anytime you're going straight you can be power-shifting.
To practice starts you would just take off with lower throttle setting, then once you get full clutch release and full throttle you can power-shift.