I think I've got it working.
root@tehserver:/etc/rc.d# ps -aux | grep ddclient
root 11400 0.0 0.8 5480 4068 pts/0 S 14:44 0:00 ddclient - sleeping for 150 seconds
root 11446 0.0 0.8 5480 4064 pts/0 S 14:45 0:00 ddclient - sleeping for 200 seconds
root@tehserver:/etc/rc.d# killall -9 ddclient
root@tehserver:/etc/rc.d# ps -aux | grep ddclient
root@tehserver:/etc/rc.d# cd /etc/ddclient
root@tehserver:/etc/ddclient# ./ddclient
root@tehserver:/etc/ddclient# ps -aux | grep ddclient
root 11580 0.0 0.8 5480 4064 pts/0 S 14:47 0:00 ddclient - sleeping for 300 seconds
root@tehserver:/etc/ddclient#