Mac users interested in Sdminst installer generally download:
SDMInst is a Java application designed to install SDM or CHDK on a Mac OSX machine. Currently it works under all versions of OSX from Panther (10.3) to Snow Leopard (10.6). It also requires version 1.4 or later of the Java Runtime.
You may find my ACID app useful in identifying and downloading a suitable build.
