@siafu: as said, the magic packet are always sent in UDP. The port "9" is only important if you have to open the port on a firewall.
The tCP port is used to test if the target system woke up. So you need to target a service on that system: ssh, http...
The most frequent issue when sending the magic packet in another subnet is the arp request. Your last router will try to send the magic packet in the target subnet but will first make an arp request. This one will not get any answer as the system is power off. To avoid this you must put a static arp in your last router.
@Larswad: You can wake up as many machine you want in the same subnet as the magic packet contains the MAC address of the target machine. I do this everyday...;-)