If doing something like:
export PATH=$PATH:~/path/where/butler/binary/is
does not work for you, you can always copy the `butler` binary to `/usr/bin`!
Make sure that it's executable first, with `chmod +x butler`
I will try that and let you know my results.
I was able to make it an executable but I was unable to add it to my PATH. It still works if I drag the file into Terminal then run commands from there.