I finally found a reasonable introduction to GNU autotools, in the form of a screencast on Youtube: Part I, Part II, Part III

Here’s the short version:

• You edit “configure.ac” and “Makefile.am”
• You run “autoreconf -i” to generate stuff
• Then you can do “configure; make; make install”

I’ll have to play with it a bit more, but so far I hate it less than CMake.