If you don't want the LEDs to be really bright, 12v LEDs will still light with 5v, and they draw less current.
Here is a custom lighting circuit and parts list. (Powered by USB plug-in)
More recently, Randy started carrying
this wire set for up to 14 LED buttons.
The buttons you linked are great for admin buttons, but I don't think you'll like them much for player buttons. YMMV.
For working with the XBox, check out
this thread and related videos by Degenatrons on "Building an Xbox powered arcade cabinet from scratch".
Scott