If you install lmod with brew, then this is how I am getting the modulefiles into my environment:
. $(brew --prefix)/opt/lmod/init/profile
export MODULEPATH_ROOT=$HOME/modulefiles
module use $MODULEPATH_ROOT/Core
where the MODULEPATH_ROOT points to where you install your module files.
Note: This assumes that you have your path set up before this so that brew --prefix can work. You can also just hard code in that path (say /usr/local/ or $HOME/.homebrew.