splitting .ly files into chunks

[Colin Cotter]

Hello ladies and gentlemen,
I am using lilypond as a composing tool -I tend to think in terms of 
manuscript so it is quicker to type stuff in than use sequencer software. 
My question is this: I am writing a piano piece with multiple parts which 
I am including into the main body of the .ly file by writing e.g. \alto,
\tenor for the different parts. Can anyone give me any tips on how to 
break the music into managable parts so I can listen to small chunks in 
midi instead of sitting through the whole piece each time? The analogue 
would be when I use \include in a LaTeX file and rem out all the \include 
bits I don't want to see in the DVI at that particular time.
COlin