I'm also member of a choir and last year we were on the eve of starting the summer program (this summer actually): The Bach Cantatas. We are a choir of amateur singers and most do not sight-read. In an effort to speed up the learning curve thus allowing the conductor to maybe add a few extra pieces if time would allow, I decied to try an make "practise" tracks for the singers.
I downloaded the demo version and proceeded to transcribe all of the choral parts onto the software. I wrote all four voices and even the piano sometimes, to fill in the short non-choir gaps.
When I was done, I proceeded to make four distinct practice files like follows:
For soprano (as an example),I replaced the sound of that voice by a piano and put the volume for sporano at max. I lowered the other voices so that the soprano line would "jump" out. I replaced the piano part with a smooth organ so as to not interfere with my soprano line. ONce done, I reduced the tempo considerably and did a "save-as" in midi format. I did this with all the voices, replacing the specific practice-voice I wanted with a strong bright piano sound. When I was done, I had four distinct midi files, one for each voice. I re-did the whole thing but with the conductor's intended tempo, thus creating 8 files.
I bought a seperate software to transform my midi files to *.wav files (thanx Mark for intending to incorporate this feature in the next version) and then burned my files onto 4 CD's, one for each voice. Every part, of every voice, on every CD was doubled, (one slow, one at tempo), so the singers could practice with a slower version and then move on to the faster version to finaly end-up being able to follow along.
The CD's were a hit, even the conductor noticed how quickly our singers were keeping up, everybody loved them and because I had burned them onto CD's they could listen to them in the car, walkman, etc.
So, that's my little history. BTW, I divided the total amount of parts I had to do into enough sessions so that I could finish before the demo period was done. I finished with one day to spare! NOw, 5 months later, I have just purchased the software and am already at work on next season's program: Brahms German Requiem.

So, Happy Easter everyone and happy noting...
-Cynthia