But I found that if the "4" and "6" keys on the number keypad are used instead, browsers are consistent. So the the following code is based on
How to cancel a keystroke before it is displayed in a text input box in NS6 by Loofa Sponge and Jim Fuqua. and uses the "4" and "6" keys to turn pages.

I've commented out all the keypress events I don't need in my script, but left them in in case you need to use them in yours. The final "if" statement contains functions called "PreviousPage()" and "NextPage()" which are specific to my own application. You can replace them with whatever function you want to occur onKeypress.

self.focus();
document.onkeypress = function (evt) {
  var r = '';
  if (document.all) {
   // r += event.ctrlKey ? 'Ctrl-' : '';
   // r += event.altKey ? 'Alt-' : '';
   // r += event.shiftKey ? 'Shift-' : '';
    r += event.keyCode;
  }
  else if (document.getElementById) {
   // r += evt.Left ? 'left-' : ''; //left and right arrow keys produce different results on every browser - and can't be distinguished accurately.
    //r += evt.ctrlKey ? 'Ctrl-' : '';
   // r += evt.altKey ? 'Alt-' : '';
  // r += evt.shiftKey ? 'Shift-' : '';
     r += evt.charCode;
  }
  else if (document.layers) {
   // r += evt.modifiers & Event.CONTROL_MASK ? 'Ctrl-' : '';
   // r += evt.modifiers & Event.ALT_MASK ? 'Alt-' : '';
  //  r += evt.modifiers & Event.SHIFT_MASK ? 'Shift-' : '';
    r += evt.which;
  }
// alert(r);
if (r==52){PreviousPage();}   //replace my PreviousPage() function with your own function
else if (r==54){NextPage();} //replace my NextPage() function with your own function

  return true;

}