Forum:Followers of Apocalypse and NCR Friendship

Under the New Vegas Endings section of this Wiki it says the Followers of the Apocalypse can be convinced to join the NCR. However i have spoken to all the creditable members of the Followers of the Apocalypse and the Colonels, Majors and Rangers of the NCR and theres nothing to get them to be friends. Does anyone know how they can be friends?