Have not drilled axle hubs, so take this for what it is worth - maybe nothing.
Axles are hardened. Different axles are hardened differently. Hubs may or may not be hardened. I don't know. Am quite sure the drilling process will need to be precision as opposed to hand drilled. Each hole needs to be precision in size, roundness, angle and position. The Mosers on my D60 were double drilled, but that would have been done in their precision manner (whatever it is) and before any hardening if the hubs are actually hardened.
Since the holes are off center - from the center of the axle - it would be difficult, not impossible, but difficult to do the job on a lathe. Length of axle makes it difficult for a milling machine too. A heavy duty drill press would probably work, but they typically are not the precision of a lathe or mill. If you think this sounds like I don't know what method the axle makers use for the drilling process, you are correct, but if I wanted to get this job done, my first step would be to call local axle shops, then machine shops, then contact the distant axle makers like Moser. From all that info I could get a very good idea of what I needed to do.
Hope this helps.
Doug '97 TJ
Creator of the CBrack
CBrack.com