Hmm, the problem is just the cable.
KW Systems offers a kit for Passat, Golf, Octavia, etc. (only for vehicles with VE TDIs with 90 or 110 horsepower). So, I would really like to keep the device, but I can still return it. However, to try it out, I need to connect it, and that's not possible without this four-pin connector.
I wouldn't want to just send all this stuff by mail and then be surprised by what I receive. Don't take it personally, it's just too complicated for me, and I know that the KW box could be registered without any major problems if I wanted to.