Unattended NTBackup to tape

How can I set up a scheduled backup to tape using XP Pro's NTbackup so that I
am never prompted for anything? I just want the backup to automatically
overwrite whatever is on the tape in the drive, regardless of tape names, set
names, etc.
I've tried every veriation I can think of and still get messages that time
out waiting for a response and keep the job from running.
I want to have the user simply take out the old tape when she gets to work,
put in a new one (any one she picks up) and have it work without intervention
for that night's backup.
Thanks.