You can use the "generic Unix" procedure above, or you can install a pre-built system using the installer package in either smlnj-ppc-110.75.dmg for PPC/Mac OS X 10.5 (Leopard), or smlnj-x86-110.75.dmg for Intel/Mac OS X 10.6 (Snow Leopard) or later. For more information, see MACOSXINSTALL.
NOTE: Mac OS X 10.8 (Mountain Lion) has a feature called gatekeeper that restricts the installation of applications to trusted sources. The installer package for SML/NJ is not signed, which means that when you try to run the installer, you will get a dialog box telling you that
"smlnj-x86-110.75.pkg" can't be opened because it is from an unidentified developer.
The workaround is to control-click on the installer package, which will offer you the option of opening the file.
We plan to release a signed version of the installer package in the near future, but we have to work out the kinks first.