OK, since so many people have answered so far, I'm gonna help those who want to know about this technique with a picture I found wandering in my wardrobe.
Here you see a plant that has flowered and fruited yet and this plant would normally die off. But why lose a healthy corm we ask?
And so the process goes like this:
I'm gonna describe it as it was written there, shorter of course, just to give you an idea:
a) Clean the corm of the soil and remove all the roots, let there be only the bulb with clearly nothing there. It's adviesed to keep the top of the cut pseudostem.
b) and c) Slowly dismantle te remnants of the p-stem and get rid off all that part by simply peeling it off and thus making it look like a downward cut with a ball-shaped, thicker item.
d) Count all the eyes you can find (distinctive small places that are unlike the tissue around) and plan the incisions so, that you will have as many finally cut parts, as there is eyes.
e) Hold the corm so that you can see all the eyes on the side and begin slow, yet precise cuts. It is adviced to do the cutting with one move, so that the wound is smooth and easy to work with.
f) After cutting the corm into smaller pieces, simply remove other wrong tissue you find in the incision. Also, some people use ash and they cover the wound with old ash.
I haven't tried it, just a translation. The pics should help.
Piece of cake.