I'm sure if there's a will, there's a way to convert it... You'd have to get creative somehow though, the shifter shaft has 270° of rotation. Maybe some kind of pulley & cable system using a return spring could be used on it (someone else here a while back I also remember had rigged up a lever on the back of the case, and had a rod through the floor that he used to manipulate it through the various positions).
One thing though, there's no detent for 4WD-HI, so you'd need to rig something to hold it there as well (and you'll also find there is infact a neutral on it, too).