I noticed that in my 2001 325ci there's a big space in my engine bay where the DSC unit was supposed to be (I didnt order it). Its linked just to about everything in the car so my first instinct is to say its not possible.
However, since BMWs already come pre-wired for their telephone accessories, garage door openers, CD changers etc, it may be as simple as ordering the unit. But I do not see it in my accessories book. You'd best call a dealership, or do what I plan on doing: putting an air compressor in where the DSC unit was supposed to be, and installing some high decibel, low pitched semi truck air horns under the hood
There are some bad drivers out there who deserve to be blasted with 125+ decibels of screaming anger