Specify s3auth.conf file per repository

I guess this is similar to #18
I was wondering if there'd be an option to specify a different config file (ideally one per bucket) to enable using multiple keys?
Maybe something like

deb [ trusted=yes s3config=/etc/apt/s3bucket1.conf ] s3://my-bucket-1 stable main
deb [ trusted=yes s3config=/etc/apt/s3bucket2.conf ] s3://my-bucket-2 stable main

Or is there any other way to obtain this functionality (except from using role based authentication)
Thanks