drh added on 2010-03-01 00:45:48:
Makefile customization is easy. Simply copy the default "Makefile" into a file named "makefile" or possibly "GNUMakefile" or "BSDMakefile" (depending on what version of make you are running) and then apply your edits to the copy. The "make" program looks for its makefile under name (GNU|BSD)Makefile, makefile, and Makefile, in that order. So if you supply one of the earlier names, the one included with the Fossil distribution will not be used.

You could also make a copy of the file into "local.mk" and then do "make -f local.mk".

ron added on 2010-03-01 06:26:10:
I dislike that solution because then the private build may break whenever the main makefile is updated.

That is why I added a "make.sh" script, which simply drives the make, giving the functionality of the (removed) config.mak without messing around with the Makefile. It is also cross-platform, working wherever "bash" is installed (maybe it works with other shells too, but I don't know).