On Unix systems.
Step 1: Grab the correct binary file (i386, or more likely x86-64) from here and install.
Step 2: Add link and run “scheme” in Terminal:
$ sudo ln -s /Applications/MIT\:GNU\ Scheme.app/Contents/Resources /usr/local/lib/mit-scheme-x86-64 $ sudo ln -s /usr/local/lib/mit-scheme-x86-64/mit-scheme /usr/bin/scheme # Note that if you've downloaded the i386 version, replace "x86-64" here with "i386"