I tried this today when I had my spinner out. It's not half-bad to do twizzles on the spinner.
I have a square metal, ball-bearing spin trainer. Don't know about a plastic footbed-version.
You're not getting the edges, though, so that's something to keep in mind.
I put the ball of my foot (or a little further forward) dead-center for the forward twizzles.
I kept my arms at my sides, shoulders level but checked into the turn direction, free foot toe-to-ankle, free knee forward, and knee locked in a bent position, I could keep the revolutions going for a long time.
Much longer than spins since there's no pull-in that can throw off your balance.
FWIW, that's what worked for me; I'm not sure much will stay with the skater on the ice, but it can't hurt. I had one DD try it, telling her to think of playing "Statues" or "Freeze Tag" where you were frozen in one position. That helped stop the movement that would throw off the turning.