Thanks for the information, unfortunately neither really worked for me with an alto sax in Eb, with version 2008. I think I have the solution which I think was suggested already:

1. Set the key to Bb, the concert key of the tune
2. Enter the chords in concert pitch, ie, Eb7, Eb7, Bb6, Bb6, transposing in my head.
3. Go to the P button and choose the Alto sax button. This only changes the display, not the pitch.
4. The chords now display in correct notation and in the correct pitch.

I believe the "P, Alto sax" steps are the same as the Opt, Pref, Notation, alto sax+9 steps.

The key signature setting to concert pitch of Bb is fixed by the composer even though the sax part is written in G. Therefore it cannot be changed. What can be changed is the screen display to give the notation for the transposed instrument, ie the Eb sax which is tuned a minor 3rd below concert. So a G on the sax is actually a Bb concert.

Do later versions of BIAB accomplish this without the mental gymnastics?

This method works but it requires the mental transposing...Please check me on this and let me know if I finally have it correct. Thanks