I use codeset 501 and 502 which is the rear USB port.
Don't mess around with anything else.
This is right out of the manual.
Using an appropriate USB cable, connect the USB2 port on the MSC-400 Rear Panel to a USB Port on a PC. The remote is programmed with Aux code set 501 or Aux 502 (Keyboard commands). The MSC-400 automatically routes Aux 501 or Aux 502 to the USB 2 port.
Most commands exist to use Windows Media Center. Just drag them on to a template you create.
You can also create any command you want with shortcut keys.
For example using CTRL+SHIFT+C as a macro will Turn on or off closed captioning.
The rear USB port works really well with Windows Media Center.
You can also launch programs by assigning Shortcut keys and creating macros.
You can find all the commands you will ever need here.