Hi Burtonski,
Welcome aboard - Please do make yourself feel right at home and stay for a spell. Hmmm - I pondered your query a bit - I don't think there are commercially available recordings of the Bruckner motets in which one can listen to each voice part separately. My suggestion is this: If you can read the notes in a choral score, listen to a recording of the motets whilst you read the notes for your individual part. I once sang in a choir where the music director had made a tape copy for each voice part with soloists singing the part with piano accompaniment.
Cheers,
CD :tiphat::tiphat::tiphat::tiphat: