score transposition problem

[Tom Cloyd]

I have a simple problem which I've never before faced, and I'm hoping 
there exists a simple solution about which someone can tell me.

I play and write music for classic guitar, so I use "\clef "treble_8"" 
in my scores (classic guitar sounds an octave lower than the music 
notation).

I want to arrange a Bach chorale for guitar. My score for the chorale is 
a nightmare. I can barely read bass clef, and can do that in my mind, 
but the scores for soprano, alto, and tenor all use C-clefs, and in a 
way that each score must be read in a unique way. I've never before seen 
a score like this. The notes fit nicely on the staff, but I cannot read 
them without a lot of mental gymnastics.

Is there a way simply to input the notes to a lilypond file as if they 
were in my normal G-clef, such that, for example, the F-clef for the 
bass part, where the note is placed on the top line of the staff (an A), 
I would record it as an F, then magically move the notes up or down 
enough semi-tones to get to a correct placement on the treble_8 clef, at 
which point I add key signature to my *.ly file and I'm ready to begin 
my transposition, using the PDF output to play from...?

This is what I'd do mentally, if that were all I COULD do, but it hurts 
my brain to think about doing this for all the parts, using C-clefs 
which are placed wherever it was convenient to place them by the 
composer (I wonder if Bach did this, or was it someone else...?).

The more I think about this the more I think there must be a way to do 
it, and only using Lilypond, but I don't know what it might be.

I look forward to the response of this forum, which I have to say is 
without doubt the most helpful of the many to which I belong.

t.