Not sure about keyboard commands, but there is PocketPC software to control your mouse pointer with your stylus on the PDA screen. you can also try Salling clicker - Works great! If you are using a Mac I wrote a few scripts to send the caller ID info from phone to computer display, it also mutes volume when a call comes in, and can even pull up Yellow page info for the caller on your computer while its ringing. I use salling clicker to display the caller ID info and control itunes remotely.
http://www.salling.com/