Downloading Emacs's code is not awkward. Note that this parameter using CO -KB can be used. Note that JPEG, LIBPNG, TIFF, XPM, and Zlib's BIN and LIB packets are downloaded on SourceForge, pay attention to XPM-NOX, do not use XPM. How to install MINGW and these packages are not, set the environment variable, run configure.bat in the NT directory, note that the above packages are included. Then make bootstrap, last make install install_dir = c: / emacs.
Find a better instruction, more than I wrote serious http://www.eqiao.com/?p=89
But I found Emacs-21.4 could not be compiled under Windows.