Restart a FAI installation without reboot

[Patrick Cervicek]

Is there an easy method to restart a FAI Installation without rebooting 
the target machine?
Usually, when an installation is finished, "<enter to reboot>" appears.
In our FAI environment, the user/admin can choose some parameters during 
the FAI installation process (in the "defclass.DEFAULT" hook) 
e.g what kind of operating system should be installed on the target 
machine. This settings can also be done remote over SSH.
This picture summarizes our installation procedure:
http://lisas.de/~patrick/blog/img/ablauf-eng.png

Sometimes it happens that the admin chooses wrong settings and needs to 
reinstall the machine. Normaly we tell our users "Could you please reboot 
the machine again with our USB stick?" and we can redefine 
our settings and restart the installation process over ssh. But sometimes 
no user is available who could do that job (or we simply don't want 
to bother our users)

I tried it with these commands and it works but it doesn't look nice

umount /var/lib/fai/config/
umount /target/dev/pts
umount /target/boot/
umount /target/sys/
umount /target/proc/
umount /target/dev
umount /target/
/etc/init.d/rcS

Is there an easier solution availabe? e.g "fai-restart-installation" ?