Letting the cut scab over for a few days will help keep it from rotting. I don't think it will root unless its in contact with soil.
I never bury the cut end, just stake it up with good contact with the soil and wait for roots. Others may have had better experience than I do as most of my 'saves' are cactus that have started to rot.
If you do cut it into more than one piece, put a little arrow on the cutting with a felt tip marker to indicate up. An upside down plant will not root. I would recomment cutting it into smaller pieces as the one large piece will be harder to root and you have more chances with more pieces to get it right. Cuttings will branch at the top cut so you will end up with fuller plants.
Daisy
