1. edit Sys:s/WHDLoad.prefs with i.e. ED2. Find Quitkey in the list, remove semikolon, change to =$5D for the *-key on the numeric keyboard. Save the file3. A restart of the Amiga might be required.
See here for the full list of the keyboard layout with their hex values
ref: http://wiki.amigaos.net/wiki/Keymap_Library#Keyboard_Layout
Credits to TroelsDK