ok, one easy change for monobright grids:
flip the order of the led brightness, so leds go low for the active step, and the other steps stay high.
change all instances of the g:led functions like so. Change:
g:led(i,9-step[2][i],i==position[2] and 15 or 3)
to
g:led(i,9-step[2][i],i==position[2] and 3 or 15)
this might look funny on varibright grids, but seems better on a monobright grid 