hi
for 20% you would use .20
your setting for 1/3=.33
as for POW, it is more or less the same as WOM.
POW, anything below 1.00 has more money on the lay side and above 1.00 has more money on the back side.
WOM, anything below .50 has more money on the lay side and above .50 has more money on the back side.
so you would use it just like WOM.
mcbee