Clown-nose blink without pre-wired alarm

[Oughourj]

Hi all,

Just picked up a 2010 135i without alarm and would REALLY like to have the blinking clown-nose on the rear view mirror to deter break-ins, mainly for where I park at work. Did some research and apparently 03/2009+ builds do NOT have the alarm system pre-wired, and confirmed this by looking under my hood (missing hood open sensor wiring).

Has anyone had success getting that light to work on non-prewired cars? I read the following on the e90 forums:

http://www.e90post.com/forums/showthread.php?t=25207

He basically builds a small circuit board with timer to an LED and plays with resistors to get the LED to blink at the same rate as a car with the alarm. Gets power off a wire in the overhead. Seeing as my car isn't pre-wired, I don't think this would work because that wire would be missing and that's a key part of his DIY; the wire supplies 4.6V and changes to 12V after turning the car off and locking it.

Thoughts/comments/suggestions?

Thanks!

[MZWIE]

The wiring is always there even if you do not have factory alarm. It's typical for BMW that way.