From MorphOS Library
Installer - Installs software by interpreting their installation scripts
SCRIPT, APPNAME, MINUSER/N, DEFUSER/N, LOGFILE/K, NOPRETEND/S, NOLOG/S, LANGUAGE/K
SCRIPT - Path to an installation script file. APPNAME - Name of the application being installed. MINUSER - The minimum possible operating mode from 0 (novice - automatic installation), 1 (beginner - limited manual control), and 2 (expert - full control) options. DEFUSER - The operating mode selected initially. LOGFILE - Full path to an installation log file. NOPRETEND - The pretend mode will not be available. NOLOG - Logging is disabled initially. LANGUAGE - Forces a language to be used.
The Installer program is usually invoked by clicking icons of installer scripts and not manually from the shell. The icons have Installer as a default tool.