I agree that if a song is in a bad key for you, you shouldn't try singing it anyway-- unless the song is very right for the role you're auditioning for (i.e. I used CORNER OF THE SKY as my audition only once-- when I auditioned, and got the title role, in "Joseph..."), but I sang that in the original key.
To transpose a song, also, you can get a MIDI of the song-- use a sheet music writer on the computer to transpose it, then convert the MIDI in the new key to a WAV and use that accompaniment CD at the audition.
I also don't know if anyone just transposes to a specific key-- to transpose the song is to move it into a comfortable key for your voice, not whatever key you like singing in (I don't know anyone who has 'a key').
And if she'll say, "My darling, I'm yours!" I'll throw away my striped tie and my best pressed tweed, all I really need is the girl...