Keyboard equivalents to up/down arrows?
I doubt it, but if you are sufficiently motivated, you might be able to use ukelele to create your own keyboard layout with arrow key equivalents on them. However, note the following caveat from the ukelele manual:


  There are some limitations imposed by Apple:
  
  
  Mapping the arrow keys to something else, or other keys to arrow keys, is problematic. It will work in some applications, but not others.
  


Suddenly, this seems like a much less attractive option.