Well, you can definitely use the ActiveX component to read out the table data, as per this sample program (in German but I'm sure you'll find the code understandable enough). I'm not sure whether you can access the geometry data, however. Hopefully this is sufficient for you.
Otherwise, you might like to try what seems like the successor to the MapKit product, RegioGraph. RegioGraph claims to be able to read
.mkb files, but I'm not sure whether it will allow you to export them as anything other than their new proprietary format,
If you speak German or can track down someone who does, I suspect you'll get better answers from the RegioGraph support forum. It seems quiet, though not abandoned.
Good luck, and be sure to write an answer here if you find a solution to your problem.