Disklavier

hi everyone, 

i have a bass amp that i would like to hook up with my disklavier.

Q: does anyone know how to "connect" the bass amp with my dgtIIxg 
disklavier so that during play only the bass track of the midi song 
goes to the bass amp and the rest of the tracks goes to the piano.  
what i'm trying to accomplish is to get a more "bass" sound. i'm 
hoping my bass amp will do the trick. thanks in advance

bob