Atleast you have that to start with!! I have nothing, there is not handsfree kit for my car. What a pain. I intend to do this also. Hopefully we will be able to work this out.
I have, not the Shop manual for my car, but I have MBUSA Technical CD on my C280, it is for the W202's. I know there is information on the technical aspects, and there has to be something in there that can help, hopefully it might work for you too. I will let you know when I look at the CD later tonight, if I can't have someone bring it to me here at work.
2006 E350 w/ 155k miles (Daily Driver)
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)