Hi,
I hate buttons and remotes, they're for jerks! - I've made a far lazier version - just wave your hand over a sensor instead.
http://luckylarry.co.uk/2010/06/arduino-redefining-the-tv-remote/
Vid also on here: Arduino TV Remote | Using a sensor to operate the TV instead… | Flickr
Makes use of an IR library here: A Multi-Protocol Infrared Remote Library for the Arduino
Which is very handy to decode any IR signal you want to work with.
Anyway - enjoy, hope others can build on it and make it better 
Cheers,
Larry