Or a sharp knife.
Just decide what lead to save and start with cutting the rizome, continue with the pot, thereafter cut as few roots as possibly. Unfortunate it is impossibly to save all the roots but try to save as many you can on the best leads and hope for the best on the rest. And if you cut it up in small bits, remember to spare at least 3-4 pseudobulbs on each part.
If you decide to cut it in just two, you can just take the knife and make the cut! Straight down the middle. Then you can carefully remove the roots you can, not belonging to each plant and just plant the two parts in separate baskets.