You need to change the number on the Ohno files before you copy them into the Lemmix folder so they are different to the original ones (if they have the same name it will just overwrite them). By default they are numbered 0-3, just change these to 5-8 (add 5 to each one).
When you want to play (or make) levels in an Ohno style you will need to change the viewer to "custom lemmings" mode unless you are playing the actual levels from ONML.
Note that if you have the Xmas data files, you can make them number 9 and use them as well
