You want to monitor this, without the program itself being bound to the port? I think you want a packet-sniffer. You could probably filter the results to selectively look at data for a single port.
If you have Sygate personal firewall, you can make a rule so that it automatically captures packets under certain conditions.
If you want a more full-fledged sniffer, I would suggest Ethereal.
As for injecting your own data... Hmm. Are you sure you don't mean that you want a proxy?
What program or port are you trying to log? Could you give us more specifics?
