Paul__B:
I haven't looked closely at the jumpers in the backpacks I have here (quite a few!), but presumed they disabled the backlight entirely if removed. If they in fact put the backlight on irrespective of software control (which does make more sense as it allows for software not doing so), then yes, you would simply put the resistor in place of the jumper.
What the jumper does can vary quit a bit board to board.
I outlined what I've seen in this response:
http://forum.arduino.cc/index.php?topic=241928.msg1744451#msg1744451
--- bill