I agree with romanza's post on this one... I didn't read past that post, so I don't know what was said after it.
Except, instead of playing them as triplets, play them as 16ths. This helps to make them not "lumpy" and makes them a lot more smooth.
Also, just a minor difference, but instead of bumping up 8 or 12 bpm each time, I only do 4 (I practice everything this way... start out at half tempo or slower, and then once it's perfect at that tempo, bump up the metronome 4 bpm. I guess the 4 bpm thing only works if you have a digital metronome come to think of it... if you don't have one though, you should go out and get one anyway