I'm just recalling this off the top of my head, but this should do it:
Remove the turret cap. Loosen the allen screw and turn the zero stop counter clockwise enough (maybe 2-3 turns CCW) so you can zero the scope. Put the turret cap on and tighten the cap screw so you can turn the turret. Once it is zeroed, pull the cap off and turn the zero stop CW until it hits the stop on the turret. Tighten the allen screw. Place the cap back on with the zero mark lined up and tighten the cap screw.