Yamaha DTXpress/DTXplorer/DTXtreme

JML:
Stewart's correct in that panning hard left and right is about the 
only way you can separate the voices into separate tracks. You could 
split the higher-end voices (snare, hi-hat and cymbals) to one 
channel, and the lower-end voices (bass and toms) to the other. Or, 
if you're laying down more of a groove recording, find an acceptable 
mating between the bass and snare (possibly even hi-hat, too) and run 
them through one channel, then run the toms and cymbals through the 
other channel.

I use two modules and have just the bass and snare running through 
module one (split to two channels), and then run toms and cymbals 
through the other module. When playing live, I run the two modules 
through a four channel mixer that I mix (sending one line to the 
main). When recording, I send four lines to the mixing board.

Oh, and panning hard left or right will not eliminate the voice 
completely from the other channel, but it's very slight.

Stephen