I will add to what Arne stated above, Once you have slowed down the pattern, REPEAT IT, REPEAT IT, over and over. But instead of thinking abou tthe fill, listen to what you are doing. Intently listen to what you are doing. Score the beat in your head and then switch around the accents - you will find a feel for the beat, you will find the groove that sets inside you so that you know where the downbeat is, and then start your fill practicing. But keep it basic at first. If the groove is dependent upon the downbeat, make sure your fill is dependent upon the downbeat (in the beginning). Speed and intensity of your fills will come, knowing the groove of the beat and making the fills tasteful for that beat is really key.
These pieces are things that I do so hopefully it will help. But don't think that after one or two 5 minute practices will lock the groove inside you - digesting what you are listening to is an art of itself.