Yes, there is a part from Mercedes to be installed in the cdc space that is left empty. You can order it from your dealer. Is a very cheap part. Now, regarding the opening of the compartment there is no solution from the Mercedes. Threre is a solution aftermarket. There is a very reliable company in Germany selling those interfaces. I order mine when I did my conversion from AUDIO 20 to NTG 2.5. The intreface module was integrated withing the wiring conversion. The company is Kabel Daviko
. Explain the problem and they will tell you what do you need.