Sure someone must have tried it before now Geoffrey, I think these drag knife attachments are spring loaded to ensure the blade stays in contact with the media & cuts correctly, the way you are looking to try wouldn't have that ability.
Other problem you might have is finding a blade with the right angle, a normal plotter blade is likely to be a bit to fragile for this sort of work so you would be looking at something a bit sturdier. Possibly scalpel or craft knife type blades.