Step one: Be able to pat your legs with this Rhythm.
Step Two: Once you have mastered Step one, pick two simple chords (like a C major triad in both hands, an octave apart) and play two against three.
Step Three: Learn the Chopin Etude in Ab major, Opus Posthumous (one of the Trios Nouvelles Etudes)
Step Four: Play Godowsky's transciption of this etude which is 2 against 3 against 4 against 5. Actually, nevermind this step.

I did the first three steps with an intermediate student of mine this semester, and she got all three things within two weeks. But if you can't tap it, don't expect to be able to play it. Tap first.
Robert Henry