Start comand prompt.
Create working folder at your convenient place and move to it.
Clone FreeCAD's newest sorce code by a following command. In this example, we use souce code rivision "fe19cb09cc7a07629ae224a64f58167780284987".
Create Visual studio solution for building by following commands.
Click FreeCAD_trunk.sln in FreeCAD-build folder and start Visual Studio.
Confirm that ALL_BUILD is selected at Solution Explorer and start building by selecting [Build]-[Build Solution] in menu bar
If your development environment is not English, Many warnig(warning C4819) may be displayed. Be that as it may, building process will be normally completed in about 10 minutes(I used Intel Core i7-2600 3.4GHz 8core CPU).
Copy all files and folders in FreeCADLibs_8.1_x86_VC9\bin folder to FreeCAD-build\bin folder
At Solution Explorer, right click FreeCADMain and set it to Startup Project.
Click [Debug]-[Start Debugging] in menu bar and start FreeCAD that you build.