Drill and tap stepper motor shaft?

I am in the process of adding stepper motors to my Taig mill. The
motors are single shafted, however I would like to be able to put
handles on the motors so I can use the mill in manual mode. While
playing with the motors today I realized that there was a hole in the
back case under the specification sticker. The hole exposes the back
of the motor shaft. Is it possible to drill & tap the back of the
shaft so I can rig up some sort of handle? Will drilling & tapping
hurt the motor?

Thank You,

Jason