you will need a cross-over serial cable, where the transmit and recieve pins are crossed between the cable ends.
In addition, you will need the protocol information on controlling your TV. This can be found either in the back of your manual, or in the service manual.
Once you have this, a new device template can be made entirely inside the web admin as a GSD device.
You can log onto the chat feature to talk to us, and we can help walk you through the process of making a device template for your TV. It is very wizard-driven.
Once this is done, we can also attempt to create a PnP script for your TV, so that it will be detected automatically in future installations.
Once this is done, your changes will be folded into LinuxMCE, so that others can use it.