This is a quick and dirty way to install the autoconf archive, “a collection of more than 500 macros for GNU Autoconf that have been contributed as free software.”
Either clone the git repository or download a tarball. Decide on a place for the macros: they will all reside in a single directory. Let’s say /usr/local/share/aclocal. Then, just copy all the .m4 files from the m4 subdirectory of the repo into /usr/local/share/aclocal. Next, set in either a system or user-specific login script, the environment variable ACLOCAL_PATH=/usr/local/share/aclocal. Like other PATH-like environment variables, the value is a colon-delimited list.