esp-open-sdk can be installed almost as described in Linux Compiler Setups.
Some problems have been reported if you build the toolchain in a case-insensitive filesystem. To avoid these issues create a case-sensitive volume:
hdiutil create ~/Desktop/eos.dmg -volname "esp-open-sdk" -size 10g -fs "Case-sensitive HFS+" hdiutil mount ~/Desktop/eos.dmg cd /Volumes/eos-open-sdk
brew install gnu-sed --with-default-names brew tap homebrew/dupes brew install gperf brew install grep