lf------ is the format of a number in binary. If you want to turn on the stay on ledges property, you put 1 in the 'l' bit, otherwise you have it as 0. Assuming you want the follow functionality off (so 'f' is 0), the binary number you want is
(Generally, the dash/unused bits can be/are meant to be left as zero.)
You must then convert that number to hexadecimal, since that is the format the .cfg editor expects. You can use the Windows calculator for that.
#%10000000 = #$80
So 80 is the value you want to put in the field.