hi there...
i do this with very simple method;
use mono test oscillators on two tracks panning hard left and right...
you reach the desired beat "frequency" with the difference between those 2 channels;
for ex. track A 220hz track B 223hz;
the diff of 3hz is "produced" by the brain as binaural beat.
However, i have found numerous papers on the net and tried the monaural beats. they showed themselves more efficient for brain entrainment, and you don't need earphones....
if you have time check this out...the piece i did with Kate Genevieve about immersive reality....
http://kategenevieve.wordpress.com/2011/11/08/no-place-embassy-court/