I try to build the jsoncpp under Visual Studio 2010 and newer and if I try it with 2008. Is there any support for newer Visual Studio versions?
I suggests that you take my patch used to build jsoncpp with cmake, and generate the visual studio project with cmake thanks to cmake -G "Visual Studio 10" in the project root.
You can find the patch here : https://sourceforge.net/tracker/?func=detail&aid=3527408&group_id=144446&atid=758828
CMake has always the solution when it comes to building.
I have modified your Scons script to an own script, so I can build the static version of the lib, but in this case I have tried to build the shared lib and I can not create the proxy lib (*.lib) on VS, because there are no export signatures. Do you have used a compiler flag for the VS export symbols?