To compile BFitler on Windows, you will need either Visual Studio .NET 2003 or Visual Studio 2005. The free Visual C++ 2003 Toolkit or Visual C++ 2005 Express Edition can also be used, but first you will have to do some work on them. The instructions for Visual C++ 2003 Toolkit are here, and for Visual C++ 2005 Express Edition - here. Previous versions of BFilter were compiled with MinGW toolchain, but that's currently not supported.

1. Download and install Python.
2. Download and install SCons.
3. Put Python (and SCons) to PATH:
   Go to Control Panel -> System -> Advanced -> Environment Variables.
   In System Variables add ;C:\Python24 to the Path variable.
4. Download builddir.7z which contains ready-to-build BFilter's dependencies. Unpack this file to a path with no spaces. I assume you've unpacked it to C:\, so that the directory structure looks like this: C:\builddir\ACE_wrappers
5. Launch the command prompt for either Visual Studio or Visual C++ Toolkit.
6. Follow the instructions in C:\builddir\readme.html to build BFilter's dependencies.
7. Download and unpack BFilter's sources to C:\builddir. The directory structure has to be like this: C:\builddir\bfilter-0.10\main
8. Download and install NSIS. I am linking to version 2.0.6, because later versions stopped bundling a header for building plugins.
9. Build BFilter:
   

   cd C:\builddir\bfilter-0.10 scons

10. Build the installer:
    

    cd packaging\windows python mkinst.py

Now you should have a file named bfilter-0.10-install.exe in C:\builddir\bfilter-0.10\packaging\windows