Hi.. 
yes, you can.. you need 2 scripts
one in /etc (for example), like this 
KO=which poweroff
echo $KO
called shut_down.sh 
and another one in /etc/cron.d/ like this
# Antivirus Statistics Crond Entry
#+-----------------------Minute           (0-59)
#|    +-------------------Hour of Day    (0-23)
#|    |    +---------------Day of Month  (1-31)
#|    |    |    +-----------Month of Year (1-12)
#|    |    |    |    +-------Day of Week   (0=Sun,6=Sat)
#v   v   v   v   v
3    0   *    *   *    root    /etc/shut_down.sh
called, for example, shutdown.cron
be sure that /etc/shut_down.sh can be executed
chmod 750 /etc/shut_down.sh
HTH
Ciao
Stefano