Yes this is correct. One thing has changed though since then: I have three branches matching my Personal build directories. release and master should be usable, experimental is not guaranteed. Note that all the build machinery is included in every source package I upload on Sourceforge, including all the necessary sources.
If you need any guidance other than: follow "buildall.sh" through every other scripts, let me know.
PS: Note that MinGW-w64 also provides a makefile maintained by JonY that should do everything for you. See http://mingw-w64.svn.sourceforge.net/viewvc/mingw-w64/experimental/buildsystem/makebuildroot.mk?revision=4779