Automatically forcing umount ncp filesystems

[A. Boggiano]

Sometimes I need to mount a Novell filesystem like this:

/sbin/ipx_configure --auto_interface=on --auto_primary=on
/usr/bin/ncpmount -S NAMEBOX -u500 -U cn=ale.ou=tecs.o=foo -Pfoobar -V 
Vol1 /mnt/Novell/

If I forgot to manually unmount it, the computer hangs at shutdown: I 
waited few minutes, after that
I pushed the poweroff button (I know... shame on me!!!) ;)

How can I avoid it ?
Can I set a timeout, somewhere ?

F12 here.

Thanks