First off, thanks to Rowan for the original guide on how to do this over at http://www.rownet.co.uk/hacking-philips-hotel-televisions/
I'm just replicating it here as another source on the interwebs, and to add a little information from my own personal experience that may help others.
When I powered on the TV in the room when I arrived, the channel was set to 'CARD-CVBS'. After trying out the steps below (which were required, I should add)...
