I did this a LONG time ago on a 3995 jukebox (IBM's optical library).  This
was ADSM 2.1 on AIX (yes, that long ago).  I used the "dsmlabel" command
from the AIX prompt, and a few shell tricks.  I had a text file with the
list of volume serial numbers, and redirected it as input to the dsmlabel
command:

/usr/lpp/adsm/server/bin> dsmlabel /"options here" < vollist.txt

The "options here" were the library and drive name, and device type.  It's
been a LONG time, so I don't remember all the parameters I had to use.
Since it pulled the volumes in sequence from the cells in the jukebox, and
I inserted them in order, it matched the external label to the ADSM label.

Or, if you're not on AIX, or don't trust the shell trick, I just checked
the Help in TSM and it shows the "label libvol" command will pull labels
from a file - so you may want to go that route.

And yes, this is a single threaded process - 1 drive at a time.

Nick Cassimatis
nickpc AT us.ibm DOT com

Today is the tomorrow of yesterday.