I agree with Don...
Just connect in the new library and stick in all the tapes.
Data/tapes are bound to a device class, then the device class is bound to a
library

What I'd do is get a list of all your tape volsers in a file and assemble
checkout commands
        checkout libvol <libname> <volname> checklabel=no remove=no
        ...
then I'd call that as a macro to clear the libvol references to the old
library
also clear all your scratch volumes in a similar way
then delete out all your drives
then update your library definition to point to the new library device
then define your new drives that are in that new library which is now
pointed to by your library definition
I'd open up the old & new libraries and get folks busy moving tapes from one
to the other...
Run an inventory on the library itself so that library sees all the newly
inserted tapes
Take that macro file that you did all the checkouts with and alter it to be
        checkin libvol <libname> <volname> checklabel=no status=private
devt=____
        ...
run that macro to pick up all your private tapes
then do some voodoo to checkin your scratch tapes

in my aix environment with a 3494 I'd use
mtlib -l/dev/lmcp# -qI | grep FF00 | cut -d' ' -f1
to find all my "inserted" tape volsers...
I can only do this since I've already checked in all my private volumes,
thus they no longer have an atl code of FF00 which is an "inserted" code for
a 3494-L12
You will have to use what is proper for the silo...

hope this helps

Dwight