I worked with Legato Networker for many years.  As far as I know Legato uses
a proprietary method for writing to tape.  It does not use any standard
utilities like CPIO or TAR.  The only suggestion would be to get a trial
copy of Legato Networker and install it.  It will give you, I believe, 45
days unlimited trial license.  To recover data from a tape without the
database or indexes you will need to scan and create them from the tape or
tapes you are restoring from.

You might be able to get a trial copy from their web site or contact the
local sales person for a trial copy.

It also would be nice if you knew what version of Networker was used to make
the backup.

Given a little time I could come up with the commands to restore the
indexes.  It's been awhile.

Hope this helps,

Mike DeMuse
DeMuse Consulting Inc.
demuse AT mn.mediaone DOT net