The Epic Level Handbook lists DCs for making people fanatics for your cause. The DCs range from 50-150. Here is the chart:
Initial Att--New Att--Hostile--Unfriendly-Indif--Friendly--Helpful--Fanatic
Hostile Less than 20, 20, 25, 35, 50, 150
Unfriendly Less than 5, 5, 15, 25, 40, 120
Indifferent ---, Less than 1, 1, 15, 30, 90
Friendly ---,---, Less than 1, 1, 20, 60
Helpful ---, ---, ---, Less than 1, 1, 50
Treat the fanatic attitude as a mind-affecting enchantment effect for purposes of immunity, save bonuses, or being detected by the Sense Motive skill. Because it is nonmagical, it can't be dispelled, however any effect that suppresses or counters mind-affecting effects (such as calm emotions) will affect it normally. A fanatic's attitude can't be further adjusted by the use of skills. The duration is one day per point of Cha bonus, if any, after which time the attitude will revert to its original state.
Fanatic description:
A Fanatic will give his/her life to serve you. Possible actions include fighting to the death against overwhelming odds, throw self in front of norushing dragon.