yo dude!
You not only have to start working on it slow, but with a great deal of continuous repetition. I would reccomend you doing it at 80bpm semi-quavers for half an hour AT LEAST for at least 3-4 days a week if u wanna achieve accuracy to it's most precise.
I've read this off at drummerworld forums that this drummer named Mike Mangani (who, in case you don't know, is the current world champion for playing the most number of single strokes in one minute. 1200+ if i'm not wrong. that's playing semiquavers at over 300bpm!!!!!!!!!! GARRRR!!!)
ok back to topic. he said that if he comes across like some stuff that's challenging to play, he'd practice it at slow tempos (60bpm-80bpm) for AT LEAST ONE AND A HALF HOUR. NINETY MINUTES. he says he usually goes up to 3 hours just staying on one exercise at that slow tempo. this way, you train muscle memory, which is the ability to have certain motions "captured" into your muscles (in this case, fingers and arms and wrists (i know wrist isn't a muscle)) so that afterwhich, you can deliver your rolls much more clearly and cleanly.
and he said something like, you can achieve speed even without practicing at fast tempos. cuz with the motions captured into your "muscles", it becomes like second nature to you. and as long as u practice slowly, and with tempo precision, more "perfect motions" will be captured. the reason why we become inconsistent is because we aren't delivering the right motions.
Personal experience - i've been practicing my double pedaling at 70bpm semiquavers for 90min 3 days straight, but i've reduced to 30min now, and i've been doing this for about 2 and a half weeks. though i've been practicing at such slow tempos, i could now play semiquavers at 180-200 pretty consistently, till after a few decades of seconds before fatigue sets in.
It feels like magic........
SORRY FOR THE LONG POST MAN!!!