I made a build of leptonica-1.73 that can be used to build Tesseract 3.04 in Visual Studio. I build leptonica under MinGW as a .dll, and then I generated a .lib file for that .dll.
The .dll itself has 5-6 other .dlls as dependencies - mostly the image backends and the MinGW runtime.
I created a zip archive that contains everything you need to use leptonica in Visual Studio - the .lib file, the header files and the dll along with the other dlls it depends on.
Here's the link - https://drive.google.com/file/d/0B9PGUhmmnsm1NVQ5NWxIdTdoaEk/view?usp=sharing. This is the zip archive.