Disklavier

hi,

i have a disklavier mark 4 and i need to transpose notes as i play.  is 
there a way to do that?  i see where it can transpose when playing back 
pre-recorded midi songs, but i can figure out how to transpose what i 
play.  

i basically put it in quiet mode where i can pick a midi instrument in 
the "Performance" menu.  that works.  but it only allows instrument 
selection & volume control it seems.   

your help is greatly appreciated!

s