This assumes you have brew installed and are comfortable using a terminal.
Following the guide on https://github.com/tpruvot/cpuminer-multi will likely lead to errors about invalid paths to OpenSSL, and neoscrypt errors to the tune of Undefined symbols for architecture x86_64 during the build. I managed to piece together different fixes into an installation that has worked for me. So I hope it works for you.
Ensure a c compiler is installed. Type g++ in the terminal and continue with the xcode installation if necessary. If it prints clang: error: no input files, then you can proceed.