Hi Derek,
I had a look at the tremelo facility on the Drawbar section of the KN7000 and have come to the conclusion that it only allows Fast or Slow, within that particular sound selection. I suppose that it's the same as a physical Leslie Rotary speaker system, which only allows these two settings...............

There may be way to get around this limitation by taking other routes through sound and effects selections, but I've not explored these possibilities.