The only way you can make them less turns lock to lock is to fit the appropriate rack and pinion inside the case, in the rack I did for roosie we used a manual rack case, I just took out the innards and replaced with matching 2.2 rack and pinion.
You need of course to be able to get the ratio you want, as having the gearing cut on a blank and getting pinion cut would be very expensive.
tabetha