What form this worship takes varies: During the time of ancient Egypt, the Mummy was sometimes revered as a lesser god (something later forbidden by the Code of Horus), while following cultures revered the Reborn as saints, angels and similar beings.
The Shemsu-Heru, Cabiri, and Amenti have varied sets of worshipers, mortal families, and even quasi-cults of scientists and occultists who have gone beyond the edge of reason. Some Amenti have their mortal families from their recent lives as their neteru, and some have the neteru of their tem-akh. Others have New Age cultists, meditation groups, and even gatherings of other supernatural beings attracted to the rebirth of Osiris.
Neteru often live near or even atop your character's tomb (the Egyptian poor of Cairo live inside tombs to save on rent), maintaining the tomb, guarding it, and performing rituals in honor of the mummy. Their knowledge of who and what he actually is may be fragmentary. It's important to note that neteru aren't slaves, and they won't mindlessly charge into battle for their patron. They may, however, be persuaded to help in whatever way they can.