Mount a small vise on a drill press table. Put two short wooden dowels in chambers across from each other, invert the cylinder and tighten the jaws of the vise on the portion of the dowels sticking out of the chambers.
Unplug the drill press. Insert your nipple wrench into the drill chuck and tighten it down. Lower the head to place the offending nipple into the wrench jaws. Lock the head in that position.
Now, slowly turn the drill chuck by hand, applying torque to the nipple. The dowels in the vise will hold the cylinder from turning so that all the torque is applied to the nipple; the drill press prevents the nipple wrench from being mis-aligned (which is the main reason most nipple wrenches are easily destroyed).
All this assumes, of course, that the appropriate doses of your favorite loosening agent have been applied first.