Thats not a clean method.
But you can clamp a part like a toolholder between your chuckyaws and turn the bottom down.
You must centre it so you don't have a large imbalance and can't more then maximum 0,5mm per step, but its possible. A better method is to clamp the tool 90° false in your toolholder, and an endmill in your chuck, but if you only have 10mm, so its no option, because many tools have square, not rectangle shafts.

Another possible solution is, you make or let make a special adapter tool that looks more or less like a lying Y. On one side its 10 mm to clamp in the turret on the other side it have a 12 or 16mm Slot for the bigger toolholders.