Why do you need a wiring diagram? With the Bliztsafe, it should be just a simple plug and play hookup. I have the Blitzsafe hookup in my 2004 E46. It's just finding the right harness and connecting the harness to the bliztsafe -- they only fit together one way.
You may already know this: the harness is located on the drivers side of the trunk. Mine was hidden deep behind the trunk liner and wrapped in a black velcro type fabric. Caution: if you are prewired for celluar phone also, the cell phone harness is almost identical except for the colors of the wires.