You cut across the came journals, from front to back. I like to cut them on a slight angle. A hacksaw works fine (but takes a while).

The slotted cam may not want to go in right away with new bearings, so I made a little handle I can bolt to the nose of the cam. I put the cam in as far as it will go, and turn it slowly as I lightly push the cam further in. The slotted journals cut their way in nicely.