Here's a few resources that you might find useful if you want to develop anything for the UltraX remote control.

MediaPortal
MediaPortal - free MediaCenter HTPC Software
Logitech UltraX Media Remote - I have yet to find any product page at logitech.com that describes the remote! Reason enough not to buy the product if you ask me.

C#
Using Raw Input from C# to handle multiple keyboards
MSDN Library - About Raw Input