If these are same style as the Magnum you simple remove the spindle shaft. On the lower portion of the spindle housing drill a thru hole and tap for a grease zerk. With that done remove the bearing inner seals. or replace them with ZZ bearings. Now think those would currently use 6305-2RS bearing which are not grease-able from the outside. Now 6305-ZZ are grease-able from the outside.
My experience with the BB Magnum spindles is that the upper spindle does not fit tight in the bearing so wears groove at the bearing. A few center punches will tight this on a new shaft which of course BB does not sell separately so I have to buy aftermarket spindle yank the spindle shafts.