How to modify calendar source files

I'm using the Calendar control with MFC through the built in default dll. Now I would like to add one new parameter to the class CXTPCalendarEvent. This parameter could be for example a client name of the event.

1) I tried to include the file XTPCalendarEvent.h in the application. But it doesn't work. I think there is conflicts between the linked calendar dll and the source event included file.

2) Then I tried to include all source calendar files in the project to replace the use of the dll. I also deleted the line "#include <XTToolkitPro.h>" in stdafx.h. But when compiling, there are error. I tried /Zm200,300... without result.

3) How can I do modification to the source code and rebuild the default dll of the Calendar.

Any general guide line would be appreciated

Sincerely,

Edouard