Take the part over to the arbor press.

You must support the part against something that will provide maximum surface area to the part, but also allow the taper pin to move at the bottom.

A piece of aluminum with a semicircular depression is perfect. You can do this either with a drill, then sawing off halfway through the diameter of the hole, or with an endmill of the right diameter.

Then cut a smaller notch the length of the depression to allow the pin to move. Again, this could be done with a drill and a saw, or an endmill.