UPDATE:

I have been at it again and I think it is a no-go as I can't interrupt signal between switch and flasher as it's one piece, short of tearing apart the oem switch which I am not going to do w/o a spare on hand.

A UK member on the MB forum did find a module from Germany that does do this as well as other functions for about 149 EUR but they don't ship to US(from website at least)and that would make it about $205+ shipping; if my conversion is accurate. looks pretty cool but I can't justify the cost as of right now, but that at least shows it can be done and its module rather than relay operated it seems.

XCar-Style - Mercedes SLK (R170) Multi Light Modul

actually looking through their site I found a crossfire module; looks the same just cheaper!

http://www.dachmodule.de/SLK--R170-/...ker-Chirp.html

translation of description from website:

"Here is our newest module !

The module fits for both the Chrysler Crossfire , as well as the Mercedes SLK R170 .

It contains the following features:


- Daytime Running Lights
- Locator lighting ( when unlocking the vehicle)
- Coming home function ( when locking the vehicle )
- Indicators comfort circuit
- Chirp control


functions:


Daytime running lights :
The low beam lights when the light is off . The parking lights will remain off here . Your safety is improved because you are perceived more easily by other road users . In some European countries it is already obligatory , even to go a day with light. With this function, you can not forget this. Switching the light this is quite normal activated and lights up at full power. In combination Insturment also you can see from original pilot light if the DRL is enabled.


locator lighting :
If you unlock your car by remote control , the fog lights activate for 30 seconds. If started within this time, the engine, this will go dark . The burn time is programmable.


Coming Home function :
If you aversperren your vehicle by remote control , the fog lights activate for 30 seconds. Are they last ride low beam and stop the motor , give you the low beams light up additionally for 30 seconds ( light time individually programmable) way.


Indicators comfort circuit :
If the turn signal lever is pressed, turn signal blinks three times automatically . This feature is standard on all modern vehicles .


Chirp control:
The module also includes a control for a sound transducer , such as that described is used in many alarm systems or U.S. vehicles . Open and obstruct your vehicle by remote control, you will each receive an acoustic acknowledgment. A corresponding siren is included.


Note:
Also suitable for vehicles with Xenon headlights .
The modules are not TÜV approved .


installation:
The installation can be made from any themselves. A very detailed , illustrated guide shows how to install step by step.


Scope of delivery:
- Module MB W170ML
- Chirp siren
- Very detailed, illustrated installation instructions"