In certain situations, arbor press throats are not large enough to accommodate both ends of a shaft or axle housing to press in new bushings or bearings. When only one end is accessible, I use the following procedure.
I press in a new bearing at the accessible end and turn a guide on a lathe to fit the I.D. of the newly installed bearing. At one end of the guide, I turn a small diameter "pin." This pin fits into a drilled and reamed mating alignment hole in a bearing driver turned to fit the bushing I.D. To operate my setup, I place the bearings on the driver and hammer them into the mating counterbore using the lower bearing for alignment.