First of all contrary to what some Drs say, you should not really try and wean off. Your cues to weaning off should be high blood pressure (so keep monitoring this), all of sudden tiredness (consider that your adrenals may finally be kicking in, high cortisol causes severe fatigue as well as low cortisol), missing a dose by accident and realizing that you don't really need it anymore cause you actually felt better without it.
I know many people who have successfully weaned off of HC or Cortef. The ones that don't are usually people that are loaded with stress they cannot escape like children or a job they cannot leave. But usually many many people wean off. It can take from 1 to 4 years sometimes to wean off from the experiences that others have shared.
AGAIN, the NTH Yahoo adrenals group can inform you greatly on this topic