If you will place the chisel on the hone sideways in front of you, then left hand hold the chisel, place right forefinger on back of chisel,
stroke from left to right, coordinating hips and elbows. You can learn to freehand chisels. Take an old beater chisel, grind a hollow face
on it rocking your body left to right. You can learn to freehand sharping in about 30 minutes. You have to lock your body and make side ways
movement locking your elbows and arms, moving laterally feet flat on the ground. Do not allow any rocking of the chisel.
It does not matter that a chisel is tapered if you use this technique. All movement has to come from the legs and hips sideways.
You have to lock your whole body and all movement comes from your lower body.
Quit saying you can't do it and learn to free hand sharpen. If I can do it, anyone can. I as clumsy as a left handed beaver.