Watch the Using Polyrhythms online guitar lesson by Stu Hamm from Stu Hamm U: Slap Bass
A certain amount of physical coordination must be achieved before you can really master a style and use it to create music that doesn't sound like an exercise, and this mastery only comes through repetition. In this segment we must train our hands and ears to accurately hear and physically play in time quarter notes, triplets, eighths and sixteenths.
Make sure to play actual triplets and not a "dotted eighth-dotted eighth-eighth note pattern. I hope that you sound better at the up and down thumb section of this than I do. We all have things we can improve on!