enzymes which hydrolyze polysaccharides would be more appropriate than  proteases. cellullose is a polysaccharide.

an [enzyme] bioreactor with a stirrer would be the vessel to conduct such an experiment, but those are $$$

something cheaper could be devised, but a method of stirring is not optional, it's a necessity.

on another note, a protease might be useful in the extraction of psilocin, for obvious reasons.