How to change key bindings on MBP By default I have to hit fn+up arrow and fn+down arrow for page up and page down actions, but those buttons are on opposite sides of the keyboard. I want to be able to do rshift+up and rshift+down.

I already tried System Preferences -> Keyboard -> Shortcuts -> App Shortcuts, but it only lets me map to menu items.
You can set system-wide keybindings via the ~/Library/Keybindings/DefaultKeyBinding.dict file (more info) however it doesn't appear to be possible to distinguish between the left and right shift keys, so I think what you want to achieve is not possible.