I can help ...
First you need a taglib port for windows :
https://code.launchpad.net/~taglib-d...lib/taglib.ext
(you needs bazaar
http://bazaar-vcs.org/Download and cmake
http://www.cmake.org/HTML/Download.html )
The last builds I did used taglib with static link (you need to make changes in the taglib cmake files) , but the default taglib config is dynamic link. You should start with the dll.
Once you have built taglib and installed it, try compiling winamp-musepack and post the ouput you get. Probably you will have to change the project files to use the taglib dll.
I'll be very happy if you manage to compile it, as I need to use a virtual machine to do it.
Nicolas