and pop the a/c fan buttons out, un clip the Bowden cables, un clip the control panel from the left side, un plug the harness and then... open the back of the control panel to access the one little Xmas light.
you will need to order it a head of time because it is not usually stocked.
I went the "el cheapo" route, and salvaged the little black plug base and soldered in a new bulb.
http://www.bmwe34.net/e34main/mainte...nel_lights.htm