1. Download
$ wget http://sourceforge.net/projects/netcat/files/netcat/0.7.1/netcat-0.7.1.tar.bz2
2. Extract
$ tar jxf netcat-0.7.1.tar.bz2
3. Patch
$ wget http://sourceforge.net/p/netcat/bugs/_discuss/thread/f8b0bf92/7d08/attachment/netcat-cygwin.patch
$ cd netcat-0.7.1
$ patch -p2 < ../netcat-0.7.1
4. Configure
$ ./configure --build=i686-pc-mingw32
5. Make
$ make
$ cp src/netcat.exe ~/bin/nc.exe