physical / virtual tape backup file at a time

Hi,
 
I am resubmitting a backup theory request that I submitted a week or two
ago, but did not receive an answer.  I am thinking I was not stating the
problem properly.
 
 
We want to be able to back up a file at a time using a virtual tape to a
physical tape.  We are not sure this is even possible - but if it is -
and you have an example of a job or set of CL that accomplishes this -
we'd be very appreciative.

Thanks,
 
Adrienne McConnon