First, get the latest source from http://www.ffmpeg.org/download.html and extract it in a convenient place, then configure it:

$ LDFLAGS=-L/c/met.no/lib CPPFLAGS=-I/c/met.no/include \
  ./configure --prefix=/c/met.no \
  --disable-ffmpeg --disable-ffplay --disable-ffserver \
  --enable-memalign-hack

Note that we've tried to trim it down a bit by disabling bits we don't need.

You can safely ignore the pr: command not found messages.

Finally, build and install:

$ make INCINSTDIR=/c/met.no/include/ffmpeg all install

The INCINSTDIR bit forces ffmpeg to install its headers in /c/met.no/include/ffmpeg instead of separate directories for each library (/c/met.no/include/libavformat, /c/met.no/include/libavutil etc.)